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Document And Entity Information - shares	9 Months Ended
Document And Entity Information - shares	Sep. 30, 2012	Oct. 31, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	ARCH COAL INC
Entity Central Index Key	0001037676
Document Type	10-Q
Document Period End Date	Sep. 30, 2012
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		212,246,799

Condensed Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues	$ 1,087,618	$ 1,198,673	$ 3,190,807	$ 3,057,139
Costs, expenses and other
Cost of sales	896,809	952,850	2,628,939	2,322,124
Depreciation, depletion and amortization	126,838	139,547	399,672	320,320
Amortization of acquired sales contracts, net	(4,093)	(12,698)	(22,561)	(5,492)
Change in fair value of coal derivatives and coal trading activities, net	5,840	8,360	(29,827)	9,248
Selling, general and administrative expenses	33,266	33,275	99,305	92,749
Legal contingencies	(79,532)		(79,532)
Mine closure and asset impairment costs	(2,194)		523,568	7,316
Goodwill impairment			115,791
Acquisition and transition costs related to ICG		4,694		46,044
Other operating income, net	(25,276)	(3,611)	(45,605)	(9,018)
Total operating expenses	951,658	1,122,417	3,589,750	2,783,291
Income (loss) from operations	135,960	76,256	(398,943)	273,848
Interest expense, net:
Interest expense	(75,710)	(77,694)	(229,210)	(154,523)
Interest income	1,459	840	3,568	2,341
Interest expense, net	(74,251)	(76,854)	(225,642)	(152,182)
Other nonoperating expense:
Bridge financing costs related to ICG				(49,490)
Net loss resulting from early retirement and refinancing of debt		(1,708)	(19,042)	(1,958)
Other nonoperating expense, Total		(1,708)	(19,042)	(51,448)
Income (loss) before income taxes	61,709	(2,306)	(643,627)	70,218
Provision for (benefit from) income taxes	15,958	(11,427)	(255,363)	(1,407)
Net income (loss)	45,751	9,121	(388,264)	71,625
Less: Net income attributable to noncontrolling interest		(231)	(268)	(822)
Net income (loss) attributable to Arch Coal, Inc.	$ 45,751	$ 8,890	$ (388,532)	$ 70,803
Earnings per common share
Basic earnings (loss) per common share	$ 0.22	$ 0.04	$ (1.83)	$ 0.39
Diluted earnings (loss) per common share	$ 0.22	$ 0.04	$ (1.83)	$ 0.39
Weighted average shares outstanding
Basic, weighted average shares outstanding	212,053	211,337	211,931	182,898
Diluted, weighted average shares outstanding	212,076	211,974	211,931	183,850
Dividends declared per common share	$ 0.03	$ 0.11	$ 0.17	$ 0.32

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income (loss)	$ 45,751	$ 9,121	$ (388,264)	$ 71,625
Other Comprehensive Income (Loss), net of income taxes [Abstract]
Pension, postretirement and other post-employment benefits, reclassifications into net income	(615)	386	(3,795)	1,249
Unrealized gains (losses) on available-for-sale securities	(555)	(569)	(241)	(1,256)
Unrealized gains and losses on derivatives, net of reclassifications into net income:
Unrealized gains (losses) on derivatives	65	(3,671)	2,816	2,703
Reclassifications of (gains) losses into net income	(347)	(3,575)	3,960	(10,059)
Total other comprehensive income (loss)	(1,452)	(7,429)	2,740	(7,363)
Total comprehensive income (loss)	$ 44,299	$ 1,692	$ (385,524)	$ 64,262

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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- Definition

Net of tax amount of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

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- Definition

Net of tax amount, before reclassification adjustments, of the change in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Also includes an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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+ Details

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 550,756	$ 138,149
Restricted cash	3,450	10,322
Short term investments	99,359
Trade accounts receivable	277,634	380,595
Other receivables	71,114	88,584
Inventories	391,526	377,490
Prepaid royalties	12,120	21,944
Deferred income taxes	65,395	42,051
Coal derivative assets	40,837	13,335
Other	67,495	110,304
Total current assets	1,579,686	1,182,774
Property, plant and equipment, net	7,372,063	7,949,150
Other assets
Prepaid royalties	85,842	86,626
Goodwill	480,312	596,103
Equity investments	237,645	225,605
Other	180,306	173,701
Total other assets	984,105	1,082,035
Total assets	9,935,854	10,213,959
Current liabilities
Accounts payable	304,442	383,782
Coal derivative liabilities	3,498	7,828
Accrued expenses and other current liabilities	355,448	348,207
Current maturities of debt and short-term borrowings	115,695	280,851
Total current liabilities	779,083	1,020,668
Long-term debt	4,465,445	3,762,297
Asset retirement obligations	426,044	446,784
Accrued pension benefits	45,160	48,244
Accrued postretirement benefits other than pension	41,061	42,309
Accrued workers' compensation	85,251	71,948
Deferred income taxes	746,079	976,753
Other noncurrent liabilities	182,464	255,382
Total liabilities	6,770,587	6,624,385
Redeemable noncontrolling interest		11,534
Stockholders' Equity
Common stock	2,141	2,136
Paid-in capital	3,024,435	3,015,349
Treasury stock, at cost	(53,848)	(53,848)
Retained earnings	197,749	622,353
Accumulated other comprehensive loss	(5,210)	(7,950)
Total stockholders' equity	3,165,267	3,578,040
Total liabilities and stockholders' equity	$ 9,935,854	$ 10,213,959

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating activties
Net income (loss)	$ (388,264)	$ 71,625
Adjustments to reconcile to cash provided by operating activities:
Depreciation, depletion and amortization	399,672	320,320
Amortization of acquired sales contracts, net	(22,561)	(5,492)
Bridge financing costs related to ICG		49,490
Net loss resulting from early retirement of debt and refinancing activities	19,042	1,958
Noncash mine closure and asset impairment costs	501,942	7,316
Goodwill impairment	115,791
Prepaid royalties expensed	19,802	26,880
Employee stock-based compensation expense	9,435	9,019
Amortization relating to financing activities	14,345	9,854
Changes in:
Receivables	102,252	(35,874)
Inventories	(16,635)	(23,716)
Coal derivative assets and liabilities	(29,523)	15,199
Accounts payable, accrued expenses and other current liabilities	(51,968)	3,742
Income taxes, net	22,048	(21,971)
Deferred income taxes	(255,530)	17,062
Other	(83,453)	25,955
Cash provided by operating activities	356,395	471,367
Investing activities
Acquisition of ICG, net of cash acquired		(2,894,339)
Change in restricted cash	6,872	(5,939)
Capital expenditures	(303,968)	(215,899)
Proceeds from dispositions of property, plant and equipment	22,624	25,133
Purchases of short term investments	(99,628)
Investments in and advances to affiliates	(12,685)	(56,827)
Purchase of noncontrolling interest	(17,500)
Additions to prepaid royalties	(9,192)	(26,135)
Cash used in investing activities	(413,477)	(3,174,006)
Financing activities
Proceeds from the issuance of senior notes		2,000,000
Proceeds from term note	1,386,000
Proceeds from the issuance of common stock, net		1,267,776
Payments to retire debt	(452,806)	(604,096)
Net increase (decrease) in borrowings under lines of credit and commercial paper program	(381,300)	283,096
Payments on term note	(3,500)
Net payments on other debt	(13,078)	(8,792)
Debt financing costs	(34,686)	(114,587)
Dividends paid	(36,072)	(57,470)
Issuance of common stock under incentive plans	5,131	1,628
Cash provided by (used in) financing activities	469,689	2,767,555
Increase (decrease) in cash and cash equivalents	412,607	64,916
Cash and cash equivalents, beginning of period	138,149	93,593
Cash and cash equivalents, end of period	$ 550,756	$ 158,509

Balance Sheet Parenthetical (Parentheticals) - $ / shares	Sep. 30, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	260,000,000	260,000,000
Common Stock, Shares, Issued	213,758,599	213,183,000

Basis Of Presentation	9 Months Ended
Basis Of Presentation	Sep. 30, 2011
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of Arch Coal, Inc. and its subsidiaries and controlled entities (the “Company”). The Company’s primary business is the production of thermal and metallurgical coal from surface and underground mines located throughout the United States, for sale to utility, industrial and export markets. On June 15, 2011, the Company acquired International Coal Group, Inc. (“ICG”). The Company currently operates 15 mining complexes in West Virginia, Kentucky, Maryland, Virginia, Illinois, Wyoming, Colorado and Utah. All subsidiaries are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three and nine month periods ended September 30, 2012 are not necessarily indicative of results to be expected for the year ending December 31, 2012. These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2011 included in the Company’s Annual Report on Form 10-K/A filed with the U.S. Securities and Exchange Commission. The Company's subsidiary Arch Western Resources, LLC (“Arch Western”) operates coal mines in Wyoming, Colorado and Utah. On April 9, 2012, Delta Housing, Inc., a subsidiary of BP p.l.c. and a joint venture partner in Arch Western, exercised their contractual right to require the Company to purchase their 0.5% common and their preferred membership interests in Arch Western. The negotiated purchase amount of $17.5 million was paid on July 2, 2012.

- Definition

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

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Accounting Policies	9 Months Ended
Accounting Policies	Sep. 30, 2012
Accounting Policies [Abstract]
Accounting Policies	Accounting Policies There is no new accounting guidance that is expected to have a significant impact on the Company’s financial statements.

Debt

9 Months Ended

Sep. 30, 2012

Debt Disclosure [Abstract]

Debt



	September 30, 2012		December 31, 2011
	(In thousands)
Indebtedness to banks under credit facilities	$	100,000	$	481,300
Term loan ($1.4 billion face value) due 2018	1,383,375		—
6.75% senior notes ($450.0 million face value) due 2013	—		450,971
8.75% senior notes ($600.0 million face value) due 2016	590,475		588,974
7.00% senior notes due 2019 at par	1,000,000		1,000,000
7.25% senior notes due 2020 at par	500,000		500,000
7.25% senior notes due 2021 at par	1,000,000		1,000,000
Other	7,290		21,903
	4,581,140		4,043,148
Less current maturities of debt and short-term borrowings	115,695		280,851
Long-term debt	$	4,465,445	$	3,762,297

The current maturities of debt include contractual maturities and amounts borrowed under our revolving credit facility and accounts receivable securitization program that the Company does not intend to refinance on a long-term basis, based on cash projections and management’s plans.

On May 16, 2012, the Company entered into an amendment to its senior secured revolving credit facility that amended certain financial maintenance covenants, suspending the Company’s compliance with the debt-to-EBITDA ratio, easing other financial covenants through September 2014 and adding defined minimum EBITDA targets. The maximum borrowing capacity of the revolving credit facility was reduced from $2 billion to $600 million. In conjunction with the amendment, the Company borrowed $1.4 billion under a six-year secured term loan facility, issued at a 1% discount. The term loan contains no financial maintenance covenants, is prepayable and is secured by the same assets as borrowings under the revolving credit facility. Quarterly principal payments of $3.5 million are due beginning in September 2012, plus interest at a rate of the greater of a LIBOR-based rate or 1.25%, plus 450 basis points. The proceeds of the term loan were used to retire all outstanding borrowings under the revolving credit facility and the outstanding $450.0 million principal amount of 6.75% Senior Notes due 2013 issued by Arch Western Finance, LLC (“Arch Western Finance”), the Company’s indirect subsidiary.

On May 16, 2012, Arch Western Finance accepted for purchase an aggregate of approximately $304.0 million principal amount of its 6.75% Senior Notes due 2013 in an initial settlement pursuant to the terms of its tender offer and consent solicitation, which commenced on May 1, 2012, and called for redemption all of the remaining notes outstanding after the completion of the tender offer. The consideration for each $1,000 of principal purchased under the tender offer and consent solicitation was $1,002.50, for a total purchase consideration of $304.8 million. On May 30, 2012, the remaining notes with an outstanding principal amount of $146.0 million were redeemed at par value.

The Company incurred financing costs of $27.4 million in conjunction with the term loan, which have been deferred on the balance sheet. The Company wrote off $17.3 million of the $24.8 million of previously deferred financing costs relating to the reduction in capacity of the senior secured revolving credit facility and $1.1 million related to the redemption of the 6.75% Senior Notes due 2013, offset by the $0.8 million of unamortized issue premium on the notes. The write-off of deferred financing fees, along with other transaction fees associated with these transactions, is reflected in “Loss on extinguishment and refinancing of debt” in the condensed consolidated statements of operations.

Since May, when borrowings under the revolving credit facility were retired with the proceeds of the term loan, we have borrowed only under the accounts receivable securitization program. At September 30, 2012, the available borrowing capacity under our lines of credit was approximately $366 million.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References + Details

Mine Closure and Asset Impairment Costs

9 Months Ended

Sep. 30, 2012

Restructuring and Related Activities [Abstract]

Restructuring and Related Activities Disclosure [Text Block]

Mine Closure and Asset Impairment Costs

In response to decreasing demand for thermal coal, the Company made the decision in the second quarter of 2012 to close four mining complexes and to temporarily idle a fifth complex, all acquired with ICG. The company also curtailed production at other Appalachia mines. These actions resulted in a total workforce reduction of approximately 750 positions. The operations had ceased production prior to June 30, 2012, but continued to ship from inventory in the third quarter of 2012. The Company will incur customary annual maintenance costs related to these properties in the future. The terms of customer contracts will be fulfilled by other operations.

The following costs are reflected in the line “Mine closure and asset impairment costs” on the condensed consolidated statements of operations for the nine months ended September 30, 2012:



Parts and supplies inventory writedown	$	2,598
Impairment of property, plant and equipment	95,641
Impairment of coal properties and deferred development costs	403,279
Royalty obligations	11,546
Employee termination benefits	12,274
Pension, postretirement and occupational disease curtailment gain, net (see notes 13 and 14)	(1,770		)
	$	523,568

The fair value of the closed or idled operations’ property, plant and equipment of approximately $51 million was based on the analysis of the marketability of thermal coal properties in the current market environment and our ability to redeploy equipment to other facilities.

The majority of the employee termination benefits were paid in the third quarter of 2012. The royalty obligations represent minimum payments on various leases and will be paid over the remaining term of the leases, through 2016.

The announcement of the closures triggered an actuarial curtailment under the Company’s sponsored pension, post-retirement medical and black lung benefit programs. Certain employees were informed that they would be terminated effective August 21, 2012, which triggered the recognition of the remaining pension plan curtailment impact in the third quarter of 2012, a curtailment gain of $2.2 million.

- Definition

The entire disclosure for restructuring and related activities. Description of restructuring activities such as exit and disposal activities, include facts and circumstances leading to the plan, the expected plan completion date, the major types of costs associated with the plan activities, total expected costs, the accrual balance at the end of the period, and the periods over which the remaining accrual will be settled.

+ References + Details

Investments in Available-for-Sale Securities

9 Months Ended

Sep. 30, 2012

Available-for-sale Securities [Abstract]

Available-for-sale Securities [Text Block]

Investments in Available-for-Sale Securities

From the proceeds of the term loan discussed in Note 3, "Debt", the Company invested in marketable debt securities, primarily highly liquid AA - rated corporate bonds, U.S. government and government agency securities. These investments are held in the custody of a major financial institution. These securities, along with the Company's investments in marketable equity securities, are classified as available-for-sale securities and, accordingly, the unrealized gains and losses are recorded through other comprehensive income.

The Company's investments in available-for-sale marketable securities are as follows:



September 30, 2012										Balance Sheet
										Classification
			Unrealized		Unrealized			Fair		Short-Term
	Cost Basis		Gains		Losses			Value		Investments		Other Assets
	(In thousands)
Available-for-sale:
U.S. government and agency securities	$	72,964	$	—	$	(157	)	$	72,807	$	72,807	$	—
Corporate notes and bonds	26,664		—		(112		)	26,552		26,552		—
Equity securities	5,271		4,678		(2,514		)	7,435		—		7,435
Total Investments	$	104,899	$	4,678	$	(2,783	)	$	106,794	$	99,359	$	7,435



December 31, 2011										Balance Sheet
										Classification
			Unrealized		Unrealized			Recorded		Short-Term
	Cost Basis		Gains		Losses			Basis		Investments		Other Assets
	(In thousands)
Available-for-sale:
Equity securities	$	5,268	$	4,394	$	(2,122	)	$	7,540	$	—	$	7,540
Total Investments	$	5,268	$	4,394	$	(2,122	)	$	7,540	$	—	$	7,540

Most of the debt securities have maturity dates in 2013, and the remainder mature in the first quarter of 2014. The Company classifies its investments as current based on the nature of the investments and their availability for use in current operations.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-Glossary Debt Security
-URI http://asc.fasb.org/extlink&oid=6509901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27290-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-Glossary Equity Security
-URI http://asc.fasb.org/extlink&oid=6511694

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 3, 19, 20, 21, 22, 137
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Goodwill	9 Months Ended
Goodwill	Sep. 30, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill During the second quarter of 2012, a significant drop in the Company’s stock price, combined with continuing weak demand for thermal coal during the quarter and the Company’s resulting production cuts, indicated that the fair value of the Company’s goodwill could be less than its carrying value. Accordingly, the Company performed the first step of the two-step goodwill impairment test as of June 30, 2012. The fair values of the reporting units were determined using a discounted cash flow (“DCF”) technique. A number of significant assumptions and estimates were involved in the application of the DCF analysis to forecast operating cash flows, including the discount rate and projections of sales volumes, selling prices and costs to produce. The value of the Company’s Black Thunder reporting unit in the Powder River Basin, where $115.8 million of goodwill had been allocated, is sensitive to market demand for thermal coal. The further weakening in thermal coal markets significantly impacted the projected demand for and pricing of coal produced at Black Thunder. In step one of the goodwill impairment testing, the fair value of the Black Thunder reporting unit did not exceed its carrying value, primarily due to the impact of lower demand on near term sales volumes and pricing. The second step of the test requires that we determine the fair value of Black Thunder’s goodwill, which involves determining the value of Black Thunder’s assets and liabilities. The Company is in the process of completing this valuation. Based on initial estimates of the fair values of the assets and liabilities and the deficit of the fair value when compared to the related book values, the Company recorded a preliminary impairment charge for the entire $115.8 million carrying value of Black Thunder's goodwill during the second quarter of 2012. The goodwill amounts allocated to certain reporting units in the Company’s Appalachia segment are sensitive to volatility in the demand for metallurgical coal. Should metallurgical coal markets weaken from the estimates used in the first step of the impairment test, affecting the estimates of volumes and pricing of metallurgical coal from the Company’s operations, it could cause the fair value of the reporting units to be less than their carrying value, requiring us to perform step 2 of the test for impairment.

Equity Investments And Membership Interests In Joint Ventures

9 Months Ended

Sep. 30, 2012

Equity Method Investments and Joint Ventures [Abstract]

Equity Investments and Membership Interests in Joint Ventures

The Company accounts for its investments and membership interests in joint ventures under the equity method of accounting if the Company has the ability to exercise significant influence, but not control, over the entity. Below are the equity method investments reflected in the condensed consolidated balance sheets:



In thousands	Knight Hawk Holdings, LLC			DKRW Advanced Fuels, LLC			Dominion Terminal Associates			Tenaska Trailblazer Partners, LLC			Millennium Bulk Terminals, LLC			Tongue River Holding Company, LLC		Total
Balance at December 31, 2011	$	135,225		$	19,715		$	16,086		$	15,266		$	26,324		$	12,989	$	225,605
Investments in affiliates	—			—			—			—			—			—		—
Advances to (distributions from) affiliates, net	(5,342		)	—			3,230			—			5,853			1,708		5,449
Equity in comprehensive income (loss)	16,033			(3,457		)	(3,625		)	(2		)	(2,358		)	—		6,591
Balance at September 30, 2012	$	145,916		$	16,258		$	15,691		$	15,264		$	29,819		$	14,697	$	237,645
Notes receivable from investees:
Balance at December 31, 2011	$	—		$	30,751		$	—		$	5,059		$	—		$	—	$	35,810
Balance at September 30, 2012	$	—		$	36,402		$	—		$	5,076		$	—		$	—	$	41,478

The Company may be required to make future contingent payments of up to $72.9 million related to development financing for certain of its equity investees. The Company’s obligation to make these payments, as well as the timing of any payments required, is contingent upon a number of factors, including project development progress, receipt of permits and construction financing.

- Definition

The entire disclosure for equity method investments and joint ventures. Equity method investments are investments that give the investor the ability to exercise significant influence over the operating and financial policies of an investee. Joint ventures are entities owned and operated by a small group of businesses as a separate and specific business or project for the mutual benefit of the members of the group.

+ References + Details

Derivatives

9 Months Ended

Sep. 30, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivatives

Diesel fuel price risk management

The Company is exposed to price risk with respect to diesel fuel purchased for use in its operations. The Company anticipates purchasing approximately 73 to 78 million gallons of diesel fuel for use in its operations during 2012. To protect the Company’s cash flows from increases in the price of diesel fuel for its operations, the Company uses forward physical diesel purchase contracts and purchased heating oil call options, and in the past, heating oil swaps. At September 30, 2012, the Company had protected the price of approximately 80% of its expected purchases for the remainder of 2012 and 67% of its 2013 purchases. At September 30, 2012, the Company had purchased heating oil call options for approximately 63.5 million gallons for the purpose of managing the price risk associated with future diesel purchases.

During the first quarter of 2012, the Company determined the effectiveness of the heating oil options could not be established as of December 31, 2011 and on an ongoing basis. As a result, the amount remaining in accumulated other comprehensive income of $8.2 million, or $5.2 million net of income taxes, was recorded in earnings, in the “other operating income, net” line on the condensed consolidated statement of operations.

The Company also purchased heating oil call options to hedge the fuel surcharges on its barge and rail shipments that cover increases in diesel fuel prices. These positions reduce the Company’s risk of cash flow fluctuations related to these surcharges but the positions are not accounted for as hedges. At September 30, 2012, the Company held purchased call options for approximately 14 million gallons for the purpose of managing the fluctuations in cash flows associated with fuel surcharges on future shipments.

Coal risk management positions

The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market in order to manage its exposure to coal prices. The Company has exposure to the risk of fluctuating coal prices related to forecasted sales or purchases of coal or to the risk of changes in the fair value of a fixed price physical sales contract. Certain derivative contracts may be designated as hedges of these risks.

At September 30, 2012, the Company held derivatives for risk management purposes that are expected to settle in the following years:



(Tons in thousands)	2012	2013	2014	2015	Total
Coal sales	2,915	5,713	4,020	720	13,368
Coal purchases	1,851	1,140	900	—	3,891

Coal trading positions

The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market for trading purposes. The Company is exposed to the risk of changes in coal prices on the value of its coal trading portfolio. The estimated future realization of the value of the trading portfolio is $3.6 million of gains in the remainder of 2012 and $1.6 million of losses in 2013.

Tabular derivatives disclosures

The Company’s contracts with certain of its counterparties allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. Such netting arrangements reduce the Company’s credit exposure related to these counterparties. For classification purposes, the Company records the net fair value of all the positions with a given counterparty as a net asset or liability in the consolidated balance sheets. The amounts shown in the table below represent the fair value position of individual contracts, and not the net position presented in the accompanying condensed consolidated balance sheets. The fair value and location of derivatives reflected in the accompanying condensed consolidated balance sheets are as follows:



	September 30, 2012								December 31, 2011
Fair Value of Derivatives	Asset			Liability					Asset			Liability
(In thousands)	Derivative			Derivative					Derivative			Derivative
Derivatives Designated as Hedging Instruments
Heating oil--diesel purchases	$	—		$	—				$	8,997		$	—
Coal	4,509			(1,679		)			1,109			—
Total	4,509			(1,679		)			10,106			—
Derivatives Not Designated as Hedging Instruments
Heating oil -- diesel purchases	10,913			(57		)			—			—
Heating oil -- fuel surcharges	2,839			—					1,797			—
Coal -- held for trading purposes	27,190			(25,171		)			15,505			(19,927		)
Coal -- risk management	45,739			(13,249		)			14,855			(6,035		)
Total	86,681			(38,477		)			32,157			(25,962		)
Total derivatives	91,190			(40,156		)			42,263			(25,962		)
Effect of counterparty netting	(36,658		)	36,658					(18,134		)	18,134
Net derivatives as classified in the balance sheets	$	54,532		$	(3,498	)	$	51,034	$	24,129		$	(7,828	)	$	16,301



		September 30, 2012			December 31, 2011
Net derivatives as reflected on the balance sheets
Heating oil	Other current assets	$	13,695		$	10,794
Coal	Coal derivative assets	40,837			13,335
	Coal derivative liabilities	(3,498		)	(7,828		)
		$	51,034		$	16,301

The Company had a current liability for the obligation to post cash collateral of $7.4 million at September 30, 2012 and a current asset for the right to reclaim cash collateral of $12.4 million at December 31, 2011. These amounts are not included with the derivatives presented in the table above and are included in “accrued expenses and other current liabilities” and “other current assets”, respectively, in the accompanying condensed consolidated balance sheets.

The effects of derivatives on measures of financial performance are as follows for the three month periods ended September 30:

Derivatives used in Cash Flow Hedging Relationships (in thousands)

For the three months ended September 30



							Gains (Losses) Reclassified
	Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)						from Other Comprehensive Income into Income (Effective Portion)
	2012			2011			2012		2011
Heating oil — diesel purchases	$	—		$	(6,386	)	$	—	$	5,122	⁽²⁾
Coal sales	259			1,820			542		466		⁽¹⁾
Coal purchases	(178		)	(1,274		)	—		—		⁽²⁾
Totals	$	81		$	(5,840	)	$	542	$	5,588

No ineffectiveness or amounts excluded from effectiveness testing relating to the Company’s cash flow hedging relationships were recognized in the results of operations in the three month periods ended September 30, 2012 and 2011.

Derivatives Not Designated as Hedging Instruments (in thousands)

For the three months ended September 30



	Gain (Loss) Recognized
	2012			2011
Coal — unrealized	$	(11,328	)	$	(6,131	)	⁽³⁾
Coal — realized	$	14,072		$	166		⁽⁴⁾
Heating oil — diesel purchases	$	5,184		$	—		⁽⁴⁾
Heating oil — fuel surcharges	$	1,092		$	(2,501	)	⁽⁴⁾

____________________________________________________________

Location in statement of operations:

(1) — Revenues

(2) — Cost of sales

(3) — Change in fair value of coal derivatives and coal trading activities, net

(4) — Other operating income, net

The effects of derivatives on measures of financial performance are as follows for the nine month periods ended September 30:

Derivatives used in Cash Flow Hedging Relationships (in thousands)

For the nine months ended September 30



							Gains (Losses) Reclassified from
	Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)						from Other Comprehensive Income into Income (Effective Portion)
	2012			2011			2012		2011
Heating oil — diesel purchases	$	—		$	1,535		$	—	$	14,946	⁽²⁾
Coal sales	4,983			4,570			1,552		790		⁽¹⁾
Coal purchases	(1,122		)	(2,053		)	—		—		⁽²⁾
Totals	$	3,861		$	4,052		$	1,552	$	15,736

No ineffectiveness or amounts excluded from effectiveness testing relating to the Company’s cash flow hedging relationships were recognized in the results of operations in the nine month periods ended September 30, 2012 and 2011.

Derivatives Not Designated as Hedging Instruments (in thousands)

For the nine months ended September 30



	Gain (Loss) Recognized
	2012			2011
Coal — unrealized	$	23,670		$	(7,550	)	⁽³⁾
Coal — realized	$	25,901		$	313		⁽⁴⁾
Heating oil — diesel purchases	$	(16,902	)	$	—		⁽⁴⁾
Heating oil — fuel surcharges	$	(1,140	)	$	(2,501	)	⁽⁴⁾

____________________________________________________________

Location in statement of operations:

(1) — Revenues

(2) — Cost of sales

(3) — Change in fair value of coal derivatives and coal trading activities, net

(4) — Other operating income, net

Related to the Company's trading portfolio, net unrealized and realized gains of $5.5 million and losses of $2.2 million were recognized during the three months ended September 30, 2012 and 2011, respectively. The Company recognized net unrealized and realized gains of $6.2 million and losses of $1.7 million during the nine months ended September 30, 2012 and 2011, respectively, related to its trading portfolio, which are included in the caption “Change in fair value of coal derivatives and coal trading activities, net” in the accompanying condensed consolidated statements of operations, and are not included in the previous tables reflecting the effects of derivatives on measures of financial performance.

Based on fair values at September 30, 2012, gains on derivative contracts designated as hedge instruments in cash flow hedges of approximately $4.0 million are expected to be reclassified from other comprehensive income into earnings during the next twelve months.

- Definition

The entire disclosure for the entity's entire derivative instruments and hedging activities. Describes an entity's risk management strategies, derivatives in hedging activities and non-hedging derivative instruments, the assets, obligations, liabilities, revenues and expenses arising therefrom, and the amounts of and methodologies and assumptions used in determining the amounts of such items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Name Accounting Standards Codification
-Topic 235
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(n))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 21: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 22: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Inventories

9 Months Ended

Sep. 30, 2012

Inventory Disclosure [Abstract]

Inventories

Inventories consist of the following:



	September 30, 2012		December 31, 2011
	(In thousands)
Coal	$	202,103	$	206,517
Repair parts and supplies	178,710		163,527
Work-in-process	10,713		7,446
	$	391,526	$	377,490

The repair parts and supplies are stated net of an allowance for slow-moving and obsolete inventories of $11.4 million at September 30, 2012, and $13.1 million at December 31, 2011.

Fair Value Measurements

9 Months Ended

Sep. 30, 2012

Fair Value Disclosures [Abstract]

Fair Value Measurements

The hierarchy of fair value measurements prioritizes the inputs to valuation techniques used to measure fair value. The levels of the hierarchy, as defined below, give the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs.

· Level 1 is defined as observable inputs such as quoted prices in active markets for identical assets. Level 1 assets include available-for-sale equity securities, U.S Treasury securities, and coal futures that are submitted for clearing on the New York Mercantile Exchange.

· Level 2 is defined as observable inputs other than Level 1 prices. These include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s level 2 assets and liabilities include U.S. government agency securities and commodity contracts (coal and heating oil) with fair values derived from quoted prices in over-the-counter markets or from prices received from direct broker quotes.

· Level 3 is defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. These include the Company’s commodity option contracts (coal and heating oil) valued using modeling techniques, such as Black-Scholes, that require the use of inputs, particularly volatility, that are rarely observable. Changes in the unobservable inputs would not have a significant impact on the reported Level 3 fair values at September 30, 2012.

The table below sets forth, by level, the Company’s financial assets and liabilities that are recorded at fair value in the accompanying condensed consolidated balance sheet:



	Fair Value at September 30, 2012
	Total		Level 1		Level 2			Level 3
	(In thousands)
Assets
Investments in marketable securities	$	106,794	$	58,109	$	48,685		$	—
Derivatives	54,532		40,884		(47		)	13,695
Total assets	$	161,326	$	98,993	$	48,638		$	13,695
Liabilities:
Derivatives	$	3,498	$	—	$	1,912		$	1,586

The Company’s contracts with certain of its counterparties allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. For classification purposes, the Company records the net fair value of all the positions with these counterparties as a net asset or liability. Each level in the table above displays the underlying contracts according to their classification in the accompanying condensed consolidated balance sheet, based on this counterparty netting.

The following table summarizes the change in the fair values of financial instruments categorized as level 3.



	Three Months Ended September 30, 2012			Nine Months Ended September 30, 2012
Balance, beginning of period	$	5,109		$	6,211
Realized and unrealized losses recognized in earnings, net	4,265			(7,331		)
Realized and unrealized losses recognized in other comprehensive income, net	—			—
Purchases	2,869			14,598
Issuances	—			—
Settlements	(134		)	(1,369		)
Ending balance	$	12,109		$	12,109

Net unrealized gains during the three month period ended September 30, 2012 related to level 3 financial instruments held on September 30, 2012 was $4.3 million. Net unrealized losses during the nine month period ended September 30, 2012 related to level 3 financial instruments held on September 30, 2012 was $3.1 million.

Fair Value of Long-Term Debt

At both September 30, 2012 and December 31, 2011, the fair value of the Company’s debt, including amounts classified as current, was $4.2 billion. Fair values are based upon observed prices in an active market when available or from valuation models using market information.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15B
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44A, 44B
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 17-22, 27, 28
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
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-Number 107
-Paragraph 15A
-Subparagraph a-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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-Paragraph 32, 33, 34
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 3, 10, 14, 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Accrued Expenses and Other Current Liabilities

9 Months Ended

Sep. 30, 2012

Accrued Expenses and Other Current Liabilities [Abstract]

Accounts Payable and Accrued Liabilities Disclosure [Text Block]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:



	September 30,		December 31,
	2012		2011
	(In thousands)
Payroll and employee benefits	$	80,782	$	65,323
Taxes other than income taxes	123,100		133,331
Interest	70,619		55,266
Acquired sales contracts	16,327		38,441
Workers’ compensation	10,155		11,666
Asset retirement obligations	44,178		27,119
Other	10,287		17,061
	$	355,448	$	348,207

Stock-Based Compensation And Other Incentive Plans	9 Months Ended
Stock-Based Compensation And Other Incentive Plans	Sep. 30, 2012
Share-based Compensation [Abstract]
Stock-Based Compensation And Other Incentive Plans	Stock-Based Compensation and Other Incentive Plans During the nine months ended September 30, 2012 the Company granted options to purchase approximately1.3 million shares of common stock with a weighted average exercise price of $13.30 per share and a weighted average grant-date fair value of $5.27 per share. The options’ fair value was determined using the Black-Scholes option pricing model, using a weighted average risk-free rate of 0.757%, a weighted average dividend yield of 2.92% and a weighted average volatility of 60.72%. The options’ expected life is 4.5 years and the options vest ratably over three years, and provide for the continuation of vesting after retirement for recipients that meet certain criteria. The expense for these options will be recognized through the date that the employee first becomes eligible to retire and is no longer required to provide service to earn all or part of the award. During the nine months ended September 30, 2012, the Company also granted restricted share awards totaling 569,550 shares whose average market price at the time of grant was $13.32. The shares vest over three years. The Company has a long-term incentive program that allows for the award of performance units. The total number of units earned by a participant is based on financial and operational performance measures, and may be paid out in cash or in shares of the Company’s common stock. The Company recognizes compensation expense over the three-year term of the grant. Amounts accrued and unpaid for all grants under the plan totaled $11.8 million and $9.6 million as of September 30, 2012 and December 31, 2011, respectively.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 50
-Section 50
-Paragraph 1
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph 64, 65, A240
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 93-6
-Paragraph 53
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Workers' Compensation Expense

9 Months Ended

Sep. 30, 2012

Workers' Compensation Expense [Abstract]

Workers' Compensation Expense

Workers’ Compensation Expense

The following table details the components of workers’ compensation expense:



	Three Months Ended September 30,					Nine Months Ended September 30,
	2012		2011			2012			2011
	(In thousands)
Service cost	$	419	$	807		$	1,458		$	1,246
Interest cost	629		619			1,708			1,177
Net amortization	—		(109		)	(574		)	(370		)
Curtailments	—		—			1,933			—
Total occupational disease	1,048		1,317			4,525			2,053
Traumatic injury claims and assessments	7,453		5,207			19,052			10,856
Total workers’ compensation expense	$	8,501	$	6,524		$	23,577		$	12,909

Employee Benefit Plans

9 Months Ended

Sep. 30, 2012

Pension and Other Postretirement Benefit Expense [Abstract]

Employee Benefit Plans

The following table details the components of pension benefit costs:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
	(In thousands)
Service cost	$	6,156		$	4,122		$	21,062		$	12,367
Interest cost	3,683			4,063			11,755			12,190
Curtailments	—			—			324			—
Expected return on plan assets	(5,508		)	(5,453		)	(16,523		)	(16,359		)
Amortization of prior service cost (credit)	273			(47		)	200			(142		)
Amortization of other actuarial losses	3,248			2,187			11,019			6,561
Net benefit cost	$	7,852		$	4,872		$	27,837		$	14,617

The following table details the components of other postretirement benefit costs (credits):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
	(In thousands)
Service cost	$	541		$	1,493		$	1,629		$	2,416
Interest cost	508			1,125			1,519			2,152
Curtailments	(2,212		)	—			(4,049		)	—
Amortization of prior service cost credits	(2,837		)	(636		)	(8,708		)	(1,773		)
Amortization of other actuarial gains	(130		)	(775		)	(391		)	(2,325		)
Net benefit cost (credit)	$	(4,130	)	$	1,207		$	(10,000	)	$	470

- Definition

The entire disclosure for pension and other postretirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-URI http://asc.fasb.org/topic&trid=2235017

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Implementation Guide (Q and A)
-Number FAS88
-Paragraph 63
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Number 87
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph q
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph h
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Earnings Per Common Share

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Earnings Per Common Share

Earnings per Common Share

The following table provides the basis for earnings per share calculations by reconciling basic and diluted weighted average shares outstanding:



	Three Months Ended September 30,		Nine Months Ended September 30,
	2012	2011	2012	2011
	(In thousands)
Weighted average shares outstanding:
Basic weighted average shares outstanding	212,053	211,337	211,931	182,898
Effect of common stock equivalents under incentive plans	23	637	—	952
Diluted weighted average shares outstanding	212,076	211,974	211,931	183,850

The weighted effect of restricted stock, restricted stock units and options for 5.8 million and 3.0 million shares of common stock for the three months ended September 30, 2012 and 2011, respectively, and 5.0 million and 2.1 million shares for the nine months ended September 30, 2012 and 2011, respectively, were excluded from the calculation of diluted weighted average shares outstanding because the effect would have been antidilutive.

Guarantees	9 Months Ended
Guarantees	Sep. 30, 2012
Guarantees [Abstract]
Guarantees	Guarantees On December 31, 2005, Arch entered into a purchase and sale agreement with Magnum Coal Company (“Magnum”) to sell certain assets to Magnum. On July 23, 2008, Patriot Coal Corporation acquired Magnum. On July 9, 2012, Patriot Coal Corporation and certain of its wholly owned subsidiaries, including Magnum, (collectively, “Patriot”) filed voluntary petitions for reorganization under Chapter 11 of the U.S. Code in the U.S. Bankruptcy Court for the Southern District of New York ("Bankruptcy Court"). The Company has agreed to continue to provide surety bonds and letters of credit for certain Magnum obligations, primarily reclamation. The surety bonding amounts are mandated by the state and are not directly related to the estimated cost to reclaim the properties. At September 30, 2012, the Company had $35.3 million of surety bonds remaining related to Magnum properties , however Patriot Coal has posted letters of credit of $16.7 million in the Company’s favor. On September 20, 2012, Patriot filed a motion in the Bankruptcy Court to reject a master coal sales and services agreement entered into on December 31, 2005 between Arch and Magnum that was established to supply coal for a sales agreement with a customer who did not consent to the assignment of their contract to Magnum. The motion is pending before the court. The underlying coal sales agreement provides the coal supplier with the ability to either ship coal or to elect to buy out of its monthly obligations at amounts that are predetermined for the remainder of the agreement. The remaining monthly buyout election payments total approximately $64 million, payable if elected through the end of the contract in 2017. If the Bankruptcy Court approves the rejection of the master coal sales agreement, the Company believes it would have the right to source the underlying contract from a variety of alternative sources, including the potential of sourcing it from its operations. The Company could elect to buy out of the contract obligations, depending on market conditions. The Company does not expect that, if elected, the monthly buyout payments would have a material impact on the Company's liquidity. Additionally, a predecessor of the Company entered into a guarantee for the delivery of coal under a contract assigned to Magnum. Patriot's motion to reject the contract has been approved by the Bankruptcy Court. If the guarantee is enforceable against the Company, then it may be required to fulfill Magnum’s delivery or payment obligations. The Company does not expect that fulfilling the guarantee would have a material impact on the Company's liquidity. Because the Company does not believe that it is probable that it would have to purchase replacement coal to fulfill the customer contract or perform under the guarantee, no losses have been recorded in the consolidated financial statements as of September 30, 2012. Should Patriot not emerge from bankruptcy, or is incapable of paying retiree medical benefits pursuant to Section 9711 of the Coal Industry Retiree Health Benefit Act of 1992 (“Coal Act”) to a certain subset of retirees, the Company could become responsible for their retiree medical obligations. The retirees were employees of certain subsidiaries sold to Magnum and their predecessor entities who retired prior to October 1, 1994. The Company does not have the information necessary to determine the potential amount of such obligations, but does not expect that the annual benefit payments would have a material impact on the Company's liquidity.

Contingencies	9 Months Ended
Contingencies	Sep. 30, 2012
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies Allegheny Energy Supply (“Allegheny”), the sole customer of coal produced at the Company’s subsidiary Wolf Run Mining Company’s (“Wolf Run”) Sycamore No. 2 mine, filed a lawsuit against Wolf Run, Hunter Ridge Holdings, Inc. (“Hunter Ridge”), and ICG in state court in Allegheny County, Pennsylvania on December 28, 2006, and amended its complaint on April 23, 2007. Allegheny claimed that Wolf Run breached a coal supply contract when it declared force majeure under the contract upon idling the Sycamore No. 2 mine in the third quarter of 2006, and that Wolf Run continued to breach the contract by failing to ship in volumes referenced in the contract. The Sycamore No. 2 mine was idled after encountering adverse geologic conditions and abandoned gas wells that were previously unidentified and unmapped. After extensive searching for gas wells and rehabilitation of the mine, it was re-opened in 2007, but with notice to Allegheny that it would necessarily operate at reduced volumes in order to safely and effectively avoid the many gas wells within the reserve. The amended complaint also alleged that the production stoppages constitute a breach of the guarantee agreement by Hunter Ridge and breach of certain representations made upon entering into the contract in early 2005. Allegheny voluntarily dropped the breach of representation claims later. Allegheny claimed that it would incur costs in excess of $100 million to purchase replacement coal over the life of the contract. ICG, Wolf Run and Hunter Ridge answered the amended complaint on August 13, 2007, disputing all of the remaining claims. On November 3, 2008, ICG, Wolf Run and Hunter Ridge filed an amended answer and counterclaim against the plaintiffs seeking to void the coal supply agreement due to, among other things, fraudulent inducement and conspiracy. On September 23, 2009, Allegheny filed a second amended complaint alleging several alternative theories of liability in its effort to extend contractual liability to ICG, which was not a party to the original contract and did not exist at the time Wolf Run and Allegheny entered into the contract. No new substantive claims were asserted. ICG answered the second amended complaint on October 13, 2009, denying all of the new claims. ICG’s counterclaim was dismissed on motion for summary judgment entered on May 11, 2010. Allegheny’s claims against ICG were also dismissed by summary judgment, but the claims against Wolf Run and Hunter Ridge were not. The court conducted a non-jury trial of this matter beginning on January 10, 2011 and concluding on February 1, 2011. At the trial, Allegheny presented its evidence for breach of contract and claimed that it is entitled to past and future damages in the aggregate of between $228.0 million and $377.0 million. Wolf Run and Hunter Ridge presented their defense of the claims, including evidence with respect to the existence of force majeure conditions and excuse under the contract and applicable law. Wolf Run and Hunter Ridge presented evidence that Allegheny’s damage calculations were significantly inflated because they were not determined as of the time of the breach and, in some instances, artificially assumed future non-delivery or did not take into account the apparent requirement to supply coal in the future. On May 2, 2011, the trial court entered a Memorandum and Verdict determining that Wolf Run had breached the coal supply contract and that the performance shortfall was not excused by force majeure. ICG and Allegheny filed post-verdict motions in the trial court and on August 23, 2011, the court denied the parties’ motions. The court entered a final judgment on August 25, 2011, in the amount of $104.1 million, which included pre-judgment interest. The parties appealed the lower court’s decision to the Superior Court of Pennsylvania. Wolf Run and Hunter Ridge have filed an appeal bond in the amount of $124.9 million. On August 13, 2012, the Superior Court of Pennsylvania ruled that the lower court should have calculated damages as of the date of breach, and remanded the matter back to the lower court with instructions to recalculate the award. This ruling resulted in a reduction of the Company's best estimate of the probable loss related to this lawsuit. In addition, the Company is a party to numerous claims and lawsuits with respect to various matters. The Company provides for costs related to contingencies when a loss is probable and the amount is reasonably determinable. As of September 30, 2012 and December 31, 2011, the Company had accrued $32.3 million and $117.2 million, respectively, for all legal matters, including $4.3 million and $6.3 million classified as current. The ultimate resolution of any such legal matter could result in outcomes which may be materially different from amounts the Company has accrued for such matters.

- Definition

The entire disclosure for commitments and contingencies.

+ References

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+ Details

Segment Information

9 Months Ended

Sep. 30, 2012

Segment Reporting [Abstract]

Segment Information

The Company has three reportable business segments, which are based on the major coal producing basins in which the Company operates. Each of these reportable business segments includes a number of mine complexes. The Company manages its coal sales by coal basin, not by individual mine complex. Geology, coal transportation routes to customers, regulatory environments and coal quality are characteristic to a basin. Accordingly, market and contract pricing have developed by coal basin. Mine operations are evaluated based on their per-ton operating costs (defined as including all mining costs but excluding pass-through transportation expenses), as well as on other non-financial measures, such as safety and environmental performance. The Company’s reportable segments are the Powder River Basin (PRB) segment, with operations in Wyoming; the Western Bituminous (WBIT) segment, with operations in Utah, Colorado and southern Wyoming; the Appalachia (APP) segment, with operations in West Virginia, Kentucky, Maryland and Virginia. The Appalachia segment includes the acquired ICG operations in Appalachia, as well as the Company’s previous Central Appalachia segment. The “Other” operating segment represents primarily the Company’s Illinois operations and ADDCAR subsidiary, which manufactures and sells its patented highwall mining system.

Operating segment results for the three and nine month periods ended September 30, 2012 and 2011 are presented below. Results for the reportable segments include all direct costs of mining, including all depreciation, depletion and amortization related to the mining operations, even if the assets are not recorded at the operating segment level. See discussion of segment assets below. Corporate, Other and Eliminations includes the change in fair value of coal derivatives and coal trading activities, net; corporate overhead; land management; other support functions; and the elimination of intercompany transactions.

The asset amounts below represent an allocation of assets consistent with the Company’s incentive compensation plans. The amounts in Corporate, Other and Eliminations represent primarily corporate assets (cash, receivables, investments, plant, property and equipment) as well as unassigned coal reserves, above-market acquired sales contracts and other unassigned assets. Goodwill is allocated to the respective reporting units, even though it may not be reflected in the subsidiaries’ financial statements.



	PRB			APP			WBIT			Other Operating Segments			Corporate, Other and Eliminations			Consolidated
	(in thousands)
Three Months Ended September 30, 2012
Revenues	$	406,719		$	436,409		$	217,963		$	26,527		$	—		$	1,087,618
Income (loss) from operations	38,873			88,695			40,828			(1,298		)	(31,138		)	135,960
Depreciation, depletion and amortization	43,944			61,596			17,881			2,594			823			126,838
Amortization of acquired sales contracts, net	(589		)	(3,711		)	—			207			—			(4,093		)
Mine closure and asset impairment costs	—			(1,801		)	(50		)	(210		)	(133		)	(2,194		)
Capital expenditures	5,620			77,772			13,510			3,640			1,353			101,895
Three Months Ended September 30, 2011
Revenues	$	394,012		$	611,403		$	168,795		$	24,463		$	—		$	1,198,673
Income (loss) from operations	38,632			63,350			24,653			(1,487		)	(48,892		)	76,256
Depreciation, depletion and amortization	42,676			73,420			19,125			3,674			652			139,547
Amortization of acquired sales contracts, net	3,802			(15,701		)	—			(832		)	33			(12,698		)



Mine closure and asset impairment costs	—			—			—		—			—			—
Capital expenditures	20,937			62,121			16,110		4,705			4,300			108,173
Nine Months Ended September 30, 2012
Revenues	$	1,130,408		$	1,409,776		$	562,074	$	88,549		$	—		$	3,190,807
Income (loss) from operations	94,163			(388,563		)	85,848		(3,757		)	(186,634		)	(398,943		)
Depreciation, depletion and amortization	122,298			210,789			54,935		9,704			1,946			399,672
Amortization of acquired sales contracts, net	(1,374		)	(21,658		)	—		471			—			(22,561		)
Mine closure and asset impairment costs	—			524,115			129		(437		)	(239		)	523,568
Total assets	2,234,941			3,846,136			676,057		454,118			2,724,602			9,935,854
Capital expenditures	15,399			222,177			42,761		8,153			15,478			303,968
Nine Months Ended September 30, 2011
Revenues	$	1,178,537		$	1,336,581		$	513,388	$	28,633		$	—		$	3,057,139
Income (loss) from operations	121,118			205,701			95,217		(1,412		)	(146,776		)	273,848
Depreciation, depletion and amortization	125,532			127,526			61,753		4,210			1,299			320,320
Amortization of acquired sales contracts, net	15,349			(19,907		)	—		(934		)	—			(5,492		)
Mine closure and asset impairment costs	—			7,316			—		—			—			7,316
Total assets	2,240,458			5,241,004			667,658		452,491			1,360,046			9,961,657
Capital expenditures	39,422			108,711			38,003		9,078			20,685			215,899

A reconciliation of segment income from operations to consolidated income before income taxes follows:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
	(in thousands)
Income (loss) from operations	$	135,960		$	76,256		$	(398,943	)	$	273,848
Interest expense	(75,710		)	(77,694		)	(229,210		)	(154,523		)
Interest income	1,459			840			3,568			2,341
Other nonoperating expense	—			(1,708		)	(19,042		)	(51,448		)
Income (loss) before income taxes	$	61,709		$	(2,306	)	$	(643,627	)	$	70,218

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

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+ Details

Supplemental Condensed Consolidating Financial Information

9 Months Ended

Sep. 30, 2012

Supplemental Condensed Consolidating Financial Information [Abstract]

Supplemental Condensed Consolidating Financial Information

Pursuant to the indentures governing Arch Coal, Inc.’s senior notes, certain wholly-owned subsidiaries of the Company have fully and unconditionally guaranteed the senior notes on a joint and several basis. The following tables present condensed consolidating financial information for (i) the Company, (ii) the issuer of the senior notes, (iii) the guarantors under the senior notes, and (iv) the entities which are not guarantors under the senior notes (Arch Receivable Company, LLC and the Company’s subsidiaries outside the U.S.):

Condensed Consolidating Statements of Operations

Three Months Ended September 30, 2012



	Parent/Issuer			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Revenues	$	—		$	1,087,618		$	—		$	—		$	1,087,618
Costs, expenses and other
Cost of sales	2,434			922,455			—			(28,080		)	896,809
Depreciation, depletion and amortization	1,400			125,429			9			—			126,838
Amortization of acquired sales contracts, net	—			(4,093		)	—			—			(4,093		)
Legal contingencies	—			(79,532		)	—			—			(79,532		)
Mine closure and asset impairment costs	—			(2,194		)	—			—			(2,194		)
Goodwill impairment	—			—			—			—			—
Selling, general and administrative expenses	22,050			11,353			1,783			(1,920		)	33,266
Change in fair value of coal derivatives and coal trading activities, net	—			5,840			—			—			5,840
Other operating (income) expense, net	(11,051		)	(44,137		)	(89		)	30,001			(25,276		)
	14,833			935,121			1,703			1			951,658
Income from investment in subsidiaries	159,653			—			—			(159,653		)	—
Income (loss) from operations	144,820			152,497			(1,703		)	(159,654		)	135,960
Interest expense, net:
Interest expense	(91,589		)	(7,021		)	(649		)	23,549			(75,710		)
Interest income	8,478			14,584			1,946			(23,549		)	1,459
	(83,111		)	7,563			1,297			—			(74,251		)
Other non-operating expense
Bridge financing costs related to ICG	—			—			—			—			—
Net loss resulting from early retirement of ICG debt	—			—			—			—			—
	—			—			—			—			—
Income (loss) before income taxes	61,709			160,060			(406		)	(159,654		)	61,709
Provision for income taxes	15,958			—			—			—			15,958
Net income (loss)	45,751			160,060			(406		)	(159,654		)	45,751
Less: Net income attributable to noncontrolling interest	—			—			—			—			—
Net income (loss) attributable to Arch Coal, Inc.	$	45,751		$	160,060		$	(406	)	$	(159,654	)	$	45,751
Total comprehensive income (loss)	$	45,494		$	158,864		$	(406	)	$	(159,653	)	$	44,299

Condensed Consolidating Statements of Operations

Nine Months Ended September 30, 2012



	Parent/Issuer			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Revenues	$	—		$	3,190,807		$	—		$	—		$	3,190,807
Costs, expenses and other
Cost of sales	7,691			2,696,114			—			(74,866		)	2,628,939
Depreciation, depletion and amortization	3,960			395,688			24			—			399,672
Amortization of acquired sales contracts, net	—			(22,561		)	—			—			(22,561		)
Legal contingencies	—			(79,532		)	—			—			(79,532		)
Mine closure and asset impairment costs	—			523,568			—			—			523,568
Goodwill impairment	—			115,791			—			—			115,791
Selling, general and administrative expenses	62,468			36,388			5,871			(5,422		)	99,305
Change in fair value of coal derivatives and coal trading activities, net	—			(29,827		)	—			—			(29,827		)
Other operating (income) expense, net	(7,692		)	(105,753		)	(12,449		)	80,289			(45,605		)
	66,427			3,529,876			(6,554		)	1			3,589,750
Income from investment in subsidiaries	(316,041		)	—			—			316,041			—
Income (loss) from operations	(382,468		)	(339,069		)	6,554			316,040			(398,943		)
Interest expense, net:
Interest expense	(263,428		)	(27,815		)	(2,382		)	64,415			(229,210		)
Interest income	19,615			42,557			5,811			(64,415		)	3,568
	(243,813		)	14,742			3,429			—			(225,642		)
Other non-operating expense
Bridge financing costs related to ICG	—			—			—			—			—
Net loss resulting from early retirement of debt	(17,349		)	(1,693		)	—			—			(19,042		)
	(17,349		)	(1,693		)	—			—			(19,042		)
Income (loss) before income taxes	(643,630		)	(326,020		)	9,983			316,040			(643,627		)
Benefit from income taxes	(256,944		)	—			1,581			—			(255,363		)
Net income (loss)	(386,686		)	(326,020		)	8,402			316,040			(388,264		)
Less: Net income attributable to noncontrolling interest	(268		)	—			—			—			(268		)
Net income (loss) attributable to Arch Coal, Inc.	$	(386,954	)	$	(326,020	)	$	8,402		$	316,040		$	(388,532	)
Total comprehensive income (loss)	$	(385,185	)	$	(324,785	)	$	8,402		$	316,044		$	(385,524	)

Condensed Consolidating Statements of Operations

Three Months Ended September 30, 2011



	Parent/Issuer			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Revenues	$	—		$	1,198,673		$	—		$	—		$	1,198,673
Costs, expenses and other
Cost of sales	7,439			971,319			—			(25,908		)	952,850
Depreciation, depletion and amortization	720			138,827			—			—			139,547
Amortization of acquired sales contracts, net	—			(12,698		)	—			—			(12,698		)
Mine closure and asset impairment costs	—			—			—			—			—
Goodwill impairment	—			—			—			—			—
Selling, general and administrative expenses	20,261			13,752			1,058			(1,796		)	33,275
Change in fair value of coal derivatives and coal trading activities, net	—			8,360			—			—			8,360
Acquisition and transition costs related to ICG	4,694			—			—			—			4,694
Other operating (income) expense, net	(6,062		)	(25,314		)	61			27,704			(3,611		)
	27,052			1,094,246			1,119			—			1,122,417
Income from investment in subsidiaries	105,198			—			—			(105,198		)	—
Income (loss) from operations	78,146			104,427			(1,119		)	(105,198		)	76,256
Interest expense, net:
Interest expense	(84,044		)	(11,060		)	(541		)	17,951			(77,694		)
Interest income	3,592			14,023			1,176			(17,951		)	840
	(80,452		)	2,963			635			—			(76,854		)
Other non-operating expense
Bridge financing costs related to ICG	—			—			—			—			—
Net loss resulting from early retirement of debt	—			(1,708		)	—			—			(1,708		)
	—			(1,708		)	—			—			(1,708		)
Income (loss) before income taxes	(2,306		)	105,682			(484		)	(105,198		)	(2,306		)
Benefit from income taxes	(11,427		)	—			—			—			(11,427		)
Net income (loss)	9,121			105,682			(484		)	(105,198		)	9,121
Less: Net income attributable to noncontrolling interest	(231		)	—			—			—			(231		)
Net income (loss) attributable to Arch Coal, Inc.	$	8,890		$	105,682		$	(484	)	$	(105,198	)	$	8,890
Total comprehensive income (loss)	$	6,119		$	101,255		$	(484	)	$	(105,198	)	$	1,692

Condensed Consolidating Statements of Operations

Nine Months Ended September 30, 2011



	Parent/Issuer			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Revenue	$	—		$	3,057,139		$	—		$	—		$	3,057,139
Costs, expenses and other
Cost of sales	15,658			2,382,406			—			(75,940		)	2,322,124
Depreciation, depletion and amortization	2,051			318,269			—			—			320,320
Amortization of acquired sales contracts, net	—			(5,492		)	—			—			(5,492		)
Mine closure and asset impairment costs	—			7,316			—			—			7,316
Goodwill impairment	—			—			—			—			—
Selling, general and administrative expenses	59,197			36,441			2,439			(5,328		)	92,749
Change in fair value of coal derivatives and coal trading activities, net	—			9,248			—			—			9,248
Acquisition and transition costs related to ICG	46,044			—			—			—			46,044
Other operating (income) expense, net	(15,460		)	(74,928		)	102			81,268			(9,018		)
	107,490			2,673,260			2,541			—			2,783,291
Income from investment in subsidiaries	388,253			—			—			(388,253		)	—
Income (loss) from operations	280,763			383,879			(2,541		)	(388,253		)	273,848
Interest expense, net:
Interest expense	(172,699		)	(34,858		)	(1,535		)	54,569			(154,523		)
Interest income	11,644			40,576			4,690			(54,569		)	2,341
	(161,055		)	5,718			3,155			—			(152,182		)
Other non-operating expense
Bridge financing costs related to ICG	(49,490		)	—			—			—			(49,490		)
Net loss resulting from early retirement of debt	—			(1,958		)	—			—			(1,958		)
	(49,490		)	(1,958		)	—			—			(51,448		)
Income (loss) before income taxes	70,218			387,639			614			(388,253		)	70,218
Benefit from income taxes	(1,407		)	—			—			—			(1,407		)
Net income (loss)	71,625			387,639			614			(388,253		)	71,625
Less: Net income attributable to noncontrolling interest	(822		)	—			—			—			(822		)
Net income (loss) attributable to Arch Coal, Inc.	$	70,803		$	387,639		$	614		$	(388,253	)	$	70,803
Total comprehensive income (loss)	$	72,511		$	379,390		$	614		$	(388,253	)	$	64,262

Condensed Consolidating Balance Sheets

September 30, 2012



	Parent/Issuer			Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Assets
Cash and cash equivalents	$	313,548		$	225,431	$	11,777		$	—		$	550,756
Restricted cash	3,450			—		—			—			3,450
Short term investments	99,359			—		—			—			99,359
Receivables	52,081			24,672		276,992			(4,997		)	348,748
Inventories	—			391,526		—			—			391,526
Other	104,507			80,901		439			—			185,847
Total current assets	572,945			722,530		289,208			(4,997		)	1,579,686

Property, plant and equipment, net	28,622			7,343,360		81			—			7,372,063

Investment in subsidiaries	8,503,465			—		—			(8,503,465		)	—
Intercompany receivables	(1,399,215		)	1,561,073		(161,858		)	—			—
Note receivable from Arch Western	675,000			—		—			(675,000		)	—
Other	184,982			799,033		90			—			984,105
Total other assets	7,964,232			2,360,106		(161,768		)	(9,178,465		)	984,105
Total assets	$	8,565,799		$	10,425,996	$	127,521		$	(9,183,462	)	$	9,935,854

Liabilities and Stockholders’ Equity
Accounts payable	$	35,157		$	269,203	$	82		$	—		$	304,442
Accrued expenses and other current liabilities	92,337			269,834		1,772			(4,997		)	358,946
Current maturities of debt and short-term borrowings	14,832			863		100,000			—			115,695
Total current liabilities	142,326			539,900		101,854			(4,997		)	779,083
Long-term debt	4,463,386			2,059		—			0			4,465,445
Note payable to Arch Coal	—			675,000		—			(675,000		)	—
Asset retirement obligations	790			425,254		—			—			426,044
Accrued pension benefits	21,125			24,035		—			—			45,160
Accrued postretirement benefits other than pension	11,733			29,328		—			—			41,061
Accrued workers’ compensation	28,129			57,122		—			—			85,251
Deferred income taxes	665,414			80,665		—			—			746,079
Other noncurrent liabilities	67,629			114,557		278			—			182,464
Total liabilities	5,400,532			1,947,920		102,132			(679,997		)	6,770,587
Redeemable noncontrolling interest	—			—		—			—			—
Stockholders’ equity	3,165,267			8,478,076		25,389			(8,503,465		)	3,165,267
Total liabilities and stockholders’ equity	$	8,565,799		$	10,425,996	$	127,521		$	(9,183,462	)	$	9,935,854

Condensed Consolidating Balance Sheets

December 31, 2011



	Parent/Issuer			Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Assets
Cash and cash equivalents	$	61,375		$	75,425	$	1,349		$	—		$	138,149
Restricted cash	10,322			—		—			—			10,322
Receivables	65,187			27,001		378,608			(1,617		)	469,179
Inventories	—			377,490		—			—			377,490
Other	81,732			105,282		620			—			187,634
Total current assets	218,616			585,198		380,577			(1,617		)	1,182,774

Property, plant and equipment, net	21,241			7,918,816		9,093			—			7,949,150

Investment in subsidiaries	8,805,731			—		—			(8,805,731		)	—
Intercompany receivables	(1,457,864		)	1,716,424		(258,560		)	—			—
Note receivable from Arch Western	225,000			—		—			(225,000		)	—
Other	184,266			897,567		202			—			1,082,035
Total other assets	7,757,133			2,613,991		(258,358		)	(9,030,731		)	1,082,035
Total assets	$	7,996,990		$	11,118,005	$	131,312		$	(9,032,348	)	$	10,213,959

Liabilities and Stockholders’ Equity
Accounts payable	$	25,409		$	358,347	$	26		$	—		$	383,782
Accrued expenses and other current liabilities	75,133			282,434		85			(1,617		)	356,035
Current maturities of debt and short-term borrowings	172,564			1,987		106,300			—			280,851
Total current liabilities	273,106			642,768		106,411			(1,617		)	1,020,668
Long-term debt	3,308,674			453,623		—			0			3,762,297
Note payable to Arch Coal	—			225,000		—			(225,000		)	—
Asset retirement obligations	877			445,907		—			—			446,784
Accrued pension benefits	19,198			29,046		—			—			48,244
Accrued postretirement benefits other than pension	13,843			28,466		—			—			42,309
Accrued workers’ compensation	17,272			54,676		—			—			71,948
Deferred income taxes	621,483			355,270		—			—			976,753
Other noncurrent liabilities	152,963			102,335		84			—			255,382
Total liabilities	4,407,416			2,337,091		106,495			(226,617		)	6,624,385
Redeemable noncontrolling interest	11,534			—		—			—			11,534
Stockholders’ equity	3,578,040			8,780,914		24,817			(8,805,731		)	3,578,040
Total liabilities and stockholders’ equity	$	7,996,990		$	11,118,005	$	131,312		$	(9,032,348	)	$	10,213,959

Condensed Consolidating Statements of Cash Flows

Nine Months Ended September 30, 2012



	Parent/Issuer			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Cash provided by (used in) operating activities	$	(500,331	)	$	771,047		$	85,679		$	—		$	356,395
Investing Activities
Change in restricted cash	6,872			—			—			—			6,872
Capital expenditures	(4,150		)	(299,818		)	—			—			(303,968		)
Proceeds from dispositions of property, plant and equipment	—			1,127			21,497			—			22,624
Investments in and advances to affiliates	(5,138		)	(9,082		)	—			1,535			(12,685		)
Purchases of short term investments	(99,628		)	—			—			—			(99,628		)
Purchase of noncontrolling interest	(17,500		)	—			—			—			(17,500		)
Additions to prepaid royalties	—			(9,192		)	—			—			(9,192		)
Cash used in investing activities	(119,544		)	(316,965		)	21,497			1,535			(413,477		)
Financing Activities
Contributions from parent	—			1,535						(1,535		)	—
Proceeds from term note	1,386,000			—			—			—			1,386,000
Payments to retire debt	—			(452,806		)	—			—			(452,806		)
Net decrease in borrowings under lines of credit and commercial paper program	(381,300		)	—			—			—			(381,300		)
Payments on term note	(3,500		)	—			—			—			(3,500		)
Net payments on other debt	(13,078		)	—			—			—			(13,078		)
Debt financing costs	(34,640		)	—			(46		)	—			(34,686		)
Dividends paid	(36,072		)	—			—			—			(36,072		)
Issuance of common stock under incentive plans	5,131			—			—			—			5,131
Transactions with affiliates, net	(50,493		)	147,195			(96,702		)	—			—
Cash provided by (used in) financing activities	872,048			(304,076		)	(96,748		)	(1,535		)	469,689
Increase in cash and cash equivalents	252,173			150,006			10,428			—			412,607
Cash and cash equivalents, beginning of period	61,375			75,425			1,349			—			138,149
Cash and cash equivalents, end of period	$	313,548		$	225,431		$	11,777		$	—		$	550,756

Condensed Consolidating Statements of Cash Flows

Nine Months Ended September 30, 2011



	Parent/Issuer			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Cash provided by (used in) operating activities	$	(444,664	)	$	896,941		$	19,090		$	—		$	471,367
Investing Activities
Acquisition of ICG, net of cash acquired	(2,894,339		)	—			—			—			(2,894,339		)
Change in restricted cash	(5,939		)	—			—			—			(5,939		)
Capital expenditures	(5,137		)	(210,660		)	(102		)	—			(215,899		)
Proceeds from dispositions of property, plant and equipment	—			25,133			—			—			25,133
Investments in and advances to affiliates	(777,341		)	(29,872		)	—			750,386			(56,827		)
Additions to prepaid royalties	—			(26,135		)	—			—			(26,135		)
Cash used in investing activities	(3,682,756		)	(241,534		)	(102		)	750,386			(3,174,006		)
Financing Activities
Proceeds from the issuance of senior notes	2,000,000			—			—			—			2,000,000
Proceeds from the issuance of common stock, net	1,267,776			—			—			—			1,267,776
Contributions from parent	—			750,386			—			(750,386		)	—
Payments to retire debt	—			(604,096		)	—			—			(604,096		)
Net decrease in borrowings under lines of credit and commercial paper program	340,000			(56,904		)	—			—			283,096
Net payments on other debt	(8,792		)	—			—			—			(8,792		)
Debt financing costs	(114,563		)	(16		)	(8		)	—			(114,587		)
Dividends paid	(57,470		)	—			—			—			(57,470		)
Issuance of common stock under incentive plans	1,628			—			—			—			1,628
Transactions with affiliates, net	742,906			(724,238		)	(18,668		)	—			—
Cash provided by (used in) financing activities	4,171,485			(634,868		)	(18,676		)	(750,386		)	2,767,555
Increase in cash and cash equivalents	44,065			20,539			312			—			64,916
Cash and cash equivalents, beginning of period	13,713			79,880			—			—			93,593
Cash and cash equivalents, end of period	$	57,778		$	100,419		$	312		$	—		$	158,509

Basis Of Presentation (Policy)	9 Months Ended
Basis Of Presentation (Policy)	Sep. 30, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements include the accounts of Arch Coal, Inc. and its subsidiaries and controlled entities (the “Company”). The Company’s primary business is the production of thermal and metallurgical coal from surface and underground mines located throughout the United States, for sale to utility, industrial and export markets. On June 15, 2011, the Company acquired International Coal Group, Inc. (“ICG”). The Company currently operates 15 mining complexes in West Virginia, Kentucky, Maryland, Virginia, Illinois, Wyoming, Colorado and Utah. All subsidiaries are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three and nine month periods ended September 30, 2012 are not necessarily indicative of results to be expected for the year ending December 31, 2012. These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2011 included in the Company’s Annual Report on Form 10-K/A filed with the U.S. Securities and Exchange Commission. The Company's subsidiary Arch Western Resources, LLC (“Arch Western”) operates coal mines in Wyoming, Colorado and Utah. On April 9, 2012, Delta Housing, Inc., a subsidiary of BP p.l.c. and a joint venture partner in Arch Western, exercised their contractual right to require the Company to purchase their 0.5% common and their preferred membership interests in Arch Western. The negotiated purchase amount of $17.5 million was paid on July 2, 2012.

- Definition

Disclosure of accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example, common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting. The accounting policy may also address the accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2197480

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 40
-Section 45
-URI http://asc.fasb.org/section&trid=2197723

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196966

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 325
-SubTopic 20
-URI http://asc.fasb.org/subtopic&trid=2197087

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.3A-02)
-URI http://asc.fasb.org/extlink&oid=6959686&loc=d3e355033-122828

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=16385135&loc=d3e33801-111570

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=18733093&loc=d3e5614-111684

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 4
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 18
-Paragraph 5, 6, 16-19
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 96-16
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 4
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 18
-Paragraph 20
-Subparagraph a(2)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 2-6
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 97-2
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph k
-Article 1

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 140
-Paragraph 46
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02, 03
-Article 3A

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 14, 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Debt (Tables)

9 Months Ended

Sep. 30, 2012

Debt Disclosure [Abstract]

Debt



	September 30, 2012		December 31, 2011
	(In thousands)
Indebtedness to banks under credit facilities	$	100,000	$	481,300
Term loan ($1.4 billion face value) due 2018	1,383,375		—
6.75% senior notes ($450.0 million face value) due 2013	—		450,971
8.75% senior notes ($600.0 million face value) due 2016	590,475		588,974
7.00% senior notes due 2019 at par	1,000,000		1,000,000
7.25% senior notes due 2020 at par	500,000		500,000
7.25% senior notes due 2021 at par	1,000,000		1,000,000
Other	7,290		21,903
	4,581,140		4,043,148
Less current maturities of debt and short-term borrowings	115,695		280,851
Long-term debt	$	4,465,445	$	3,762,297

Mine Closure and Asset Impairment Costs (Tables)

9 Months Ended

Sep. 30, 2012

Restructuring and Related Activities [Abstract]

Schedule of Restructuring and Related Costs [Table Text Block]

The following costs are reflected in the line “Mine closure and asset impairment costs” on the condensed consolidated statements of operations for the nine months ended September 30, 2012:



Parts and supplies inventory writedown	$	2,598
Impairment of property, plant and equipment	95,641
Impairment of coal properties and deferred development costs	403,279
Royalty obligations	11,546
Employee termination benefits	12,274
Pension, postretirement and occupational disease curtailment gain, net (see notes 13 and 14)	(1,770		)
	$	523,568

Investments in Available-for-Sale Securities (Tables)

9 Months Ended

Sep. 30, 2012

Available-for-sale Securities [Abstract]

Available-for-sale Securities [Table Text Block]

The Company's investments in available-for-sale marketable securities are as follows:



September 30, 2012										Balance Sheet
										Classification
			Unrealized		Unrealized			Fair		Short-Term
	Cost Basis		Gains		Losses			Value		Investments		Other Assets
	(In thousands)
Available-for-sale:
U.S. government and agency securities	$	72,964	$	—	$	(157	)	$	72,807	$	72,807	$	—
Corporate notes and bonds	26,664		—		(112		)	26,552		26,552		—
Equity securities	5,271		4,678		(2,514		)	7,435		—		7,435
Total Investments	$	104,899	$	4,678	$	(2,783	)	$	106,794	$	99,359	$	7,435



December 31, 2011										Balance Sheet
										Classification
			Unrealized		Unrealized			Recorded		Short-Term
	Cost Basis		Gains		Losses			Basis		Investments		Other Assets
	(In thousands)
Available-for-sale:
Equity securities	$	5,268	$	4,394	$	(2,122	)	$	7,540	$	—	$	7,540
Total Investments	$	5,268	$	4,394	$	(2,122	)	$	7,540	$	—	$	7,540

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27337-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27198-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27161-111563

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27290-111563

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 19, 20, 21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 17
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 03-1
-Paragraph 21
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Equity Investments And Membership Interests In Joint Ventures (Tables)

9 Months Ended

Sep. 30, 2012

Equity Method Investments and Joint Ventures [Abstract]

Schedule Of Equity Method Investments

Below are the equity method investments reflected in the condensed consolidated balance sheets:



In thousands	Knight Hawk Holdings, LLC			DKRW Advanced Fuels, LLC			Dominion Terminal Associates			Tenaska Trailblazer Partners, LLC			Millennium Bulk Terminals, LLC			Tongue River Holding Company, LLC		Total
Balance at December 31, 2011	$	135,225		$	19,715		$	16,086		$	15,266		$	26,324		$	12,989	$	225,605
Investments in affiliates	—			—			—			—			—			—		—
Advances to (distributions from) affiliates, net	(5,342		)	—			3,230			—			5,853			1,708		5,449
Equity in comprehensive income (loss)	16,033			(3,457		)	(3,625		)	(2		)	(2,358		)	—		6,591
Balance at September 30, 2012	$	145,916		$	16,258		$	15,691		$	15,264		$	29,819		$	14,697	$	237,645
Notes receivable from investees:
Balance at December 31, 2011	$	—		$	30,751		$	—		$	5,059		$	—		$	—	$	35,810
Balance at September 30, 2012	$	—		$	36,402		$	—		$	5,076		$	—		$	—	$	41,478

Derivatives (Tables)

9 Months Ended

Sep. 30, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Price Risk Derivatives

At September 30, 2012, the Company held derivatives for risk management purposes that are expected to settle in the following years:



(Tons in thousands)	2012	2013	2014	2015	Total
Coal sales	2,915	5,713	4,020	720	13,368
Coal purchases	1,851	1,140	900	—	3,891

Disclosure Of Fair Value Of Derivatives



	September 30, 2012								December 31, 2011
Fair Value of Derivatives	Asset			Liability					Asset			Liability
(In thousands)	Derivative			Derivative					Derivative			Derivative
Derivatives Designated as Hedging Instruments
Heating oil--diesel purchases	$	—		$	—				$	8,997		$	—
Coal	4,509			(1,679		)			1,109			—
Total	4,509			(1,679		)			10,106			—
Derivatives Not Designated as Hedging Instruments
Heating oil -- diesel purchases	10,913			(57		)			—			—
Heating oil -- fuel surcharges	2,839			—					1,797			—
Coal -- held for trading purposes	27,190			(25,171		)			15,505			(19,927		)
Coal -- risk management	45,739			(13,249		)			14,855			(6,035		)
Total	86,681			(38,477		)			32,157			(25,962		)
Total derivatives	91,190			(40,156		)			42,263			(25,962		)
Effect of counterparty netting	(36,658		)	36,658					(18,134		)	18,134
Net derivatives as classified in the balance sheets	$	54,532		$	(3,498	)	$	51,034	$	24,129		$	(7,828	)	$	16,301



		September 30, 2012			December 31, 2011
Net derivatives as reflected on the balance sheets
Heating oil	Other current assets	$	13,695		$	10,794
Coal	Coal derivative assets	40,837			13,335
	Coal derivative liabilities	(3,498		)	(7,828		)
		$	51,034		$	16,301

Effects Of Derivatives On Measures Of Financial Performance

Derivatives used in Cash Flow Hedging Relationships (in thousands)

For the three months ended September 30



							Gains (Losses) Reclassified
	Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)						from Other Comprehensive Income into Income (Effective Portion)
	2012			2011			2012		2011
Heating oil — diesel purchases	$	—		$	(6,386	)	$	—	$	5,122	⁽²⁾
Coal sales	259			1,820			542		466		⁽¹⁾
Coal purchases	(178		)	(1,274		)	—		—		⁽²⁾
Totals	$	81		$	(5,840	)	$	542	$	5,588

Derivatives Not Designated as Hedging Instruments (in thousands)

For the three months ended September 30



	Gain (Loss) Recognized
	2012			2011
Coal — unrealized	$	(11,328	)	$	(6,131	)	⁽³⁾
Coal — realized	$	14,072		$	166		⁽⁴⁾
Heating oil — diesel purchases	$	5,184		$	—		⁽⁴⁾
Heating oil — fuel surcharges	$	1,092		$	(2,501	)	⁽⁴⁾

____________________________________________________________

Location in statement of operations:

(1) — Revenues

(2) — Cost of sales

(3) — Change in fair value of coal derivatives and coal trading activities, net

(4) — Other operating income, net

The effects of derivatives on measures of financial performance are as follows for the nine month periods ended September 30:

Derivatives used in Cash Flow Hedging Relationships (in thousands)

For the nine months ended September 30



							Gains (Losses) Reclassified from
	Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)						from Other Comprehensive Income into Income (Effective Portion)
	2012			2011			2012		2011
Heating oil — diesel purchases	$	—		$	1,535		$	—	$	14,946	⁽²⁾
Coal sales	4,983			4,570			1,552		790		⁽¹⁾
Coal purchases	(1,122		)	(2,053		)	—		—		⁽²⁾
Totals	$	3,861		$	4,052		$	1,552	$	15,736

No ineffectiveness or amounts excluded from effectiveness testing relating to the Company’s cash flow hedging relationships were recognized in the results of operations in the nine month periods ended September 30, 2012 and 2011.

Derivatives Not Designated as Hedging Instruments (in thousands)

For the nine months ended September 30



	Gain (Loss) Recognized
	2012			2011
Coal — unrealized	$	23,670		$	(7,550	)	⁽³⁾
Coal — realized	$	25,901		$	313		⁽⁴⁾
Heating oil — diesel purchases	$	(16,902	)	$	—		⁽⁴⁾
Heating oil — fuel surcharges	$	(1,140	)	$	(2,501	)	⁽⁴⁾

____________________________________________________________

Location in statement of operations:

(1) — Revenues

(2) — Cost of sales

(3) — Change in fair value of coal derivatives and coal trading activities, net

(4) — Other operating income, net

- Definition

Tabular disclosure of the location and amount of gains and losses reported in the statement of financial performance, or when applicable, the statement of financial position. For example, (a) gains and losses recognized in the income statement on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges and (b) gains and losses initially recognized in other comprehensive income on derivative instruments designated and qualifying as cash flow hedges.

+ References + Details

Inventories (Tables)

9 Months Ended

Sep. 30, 2012

Inventory Disclosure [Abstract]

Inventories

Inventories consist of the following:



	September 30, 2012		December 31, 2011
	(In thousands)
Coal	$	202,103	$	206,517
Repair parts and supplies	178,710		163,527
Work-in-process	10,713		7,446
	$	391,526	$	377,490

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value Disclosures [Abstract]

Summary Of Financial Assets And Liabilities Accounted For At Fair Value

The table below sets forth, by level, the Company’s financial assets and liabilities that are recorded at fair value in the accompanying condensed consolidated balance sheet:



	Fair Value at September 30, 2012
	Total		Level 1		Level 2			Level 3
	(In thousands)
Assets
Investments in marketable securities	$	106,794	$	58,109	$	48,685		$	—
Derivatives	54,532		40,884		(47		)	13,695
Total assets	$	161,326	$	98,993	$	48,638		$	13,695
Liabilities:
Derivatives	$	3,498	$	—	$	1,912		$	1,586

Summary Of Change In The Fair Values Of Financial Instruments Categorized As Level 3

The following table summarizes the change in the fair values of financial instruments categorized as level 3.



	Three Months Ended September 30, 2012			Nine Months Ended September 30, 2012
Balance, beginning of period	$	5,109		$	6,211
Realized and unrealized losses recognized in earnings, net	4,265			(7,331		)
Realized and unrealized losses recognized in other comprehensive income, net	—			—
Purchases	2,869			14,598
Issuances	—			—
Settlements	(134		)	(1,369		)
Ending balance	$	12,109		$	12,109

- Definition

Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.

+ References + Details

Accrued Expenses and Other Current Liabilities Accrued Expenses and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 2012

Accrued Expenses and Other Current Liabilities [Abstract]

Schedule of Accrued Liabilities [Table Text Block]

Accrued expenses and other current liabilities consist of the following:



	September 30,		December 31,
	2012		2011
	(In thousands)
Payroll and employee benefits	$	80,782	$	65,323
Taxes other than income taxes	123,100		133,331
Interest	70,619		55,266
Acquired sales contracts	16,327		38,441
Workers’ compensation	10,155		11,666
Asset retirement obligations	44,178		27,119
Other	10,287		17,061
	$	355,448	$	348,207

Workers' Compensation Expense (Tables)

9 Months Ended

Sep. 30, 2012

Workers' Compensation Expense [Abstract]

Workers' Compensation Expense

The following table details the components of workers’ compensation expense:



	Three Months Ended September 30,					Nine Months Ended September 30,
	2012		2011			2012			2011
	(In thousands)
Service cost	$	419	$	807		$	1,458		$	1,246
Interest cost	629		619			1,708			1,177
Net amortization	—		(109		)	(574		)	(370		)
Curtailments	—		—			1,933			—
Total occupational disease	1,048		1,317			4,525			2,053
Traumatic injury claims and assessments	7,453		5,207			19,052			10,856
Total workers’ compensation expense	$	8,501	$	6,524		$	23,577		$	12,909

Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2012

Pension and Other Postretirement Benefit Expense [Abstract]

Pension Benefit Costs

The following table details the components of pension benefit costs:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
	(In thousands)
Service cost	$	6,156		$	4,122		$	21,062		$	12,367
Interest cost	3,683			4,063			11,755			12,190
Curtailments	—			—			324			—
Expected return on plan assets	(5,508		)	(5,453		)	(16,523		)	(16,359		)
Amortization of prior service cost (credit)	273			(47		)	200			(142		)
Amortization of other actuarial losses	3,248			2,187			11,019			6,561
Net benefit cost	$	7,852		$	4,872		$	27,837		$	14,617

Other Postretirement Benefit Costs

The following table details the components of other postretirement benefit costs (credits):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
	(In thousands)
Service cost	$	541		$	1,493		$	1,629		$	2,416
Interest cost	508			1,125			1,519			2,152
Curtailments	(2,212		)	—			(4,049		)	—
Amortization of prior service cost credits	(2,837		)	(636		)	(8,708		)	(1,773		)
Amortization of other actuarial gains	(130		)	(775		)	(391		)	(2,325		)
Net benefit cost (credit)	$	(4,130	)	$	1,207		$	(10,000	)	$	470

- Definition

Tabular disclosure of one or more of the entity's defined benefit pension plans or one or more other defined benefit postretirement plans, separately for pension plans and other postretirement benefit plans including the entity's schedule of fair value of plan assets for defined benefit or other postretirement plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e2439-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e2417-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e2410-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=21916443&loc=d3e4179-114921

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 4, 7, 16, 20, 21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5, 6, 7
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Earnings per Common Share (Tables)

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Earnings per Share

The following table provides the basis for earnings per share calculations by reconciling basic and diluted weighted average shares outstanding:



	Three Months Ended September 30,		Nine Months Ended September 30,
	2012	2011	2012	2011
	(In thousands)
Weighted average shares outstanding:
Basic weighted average shares outstanding	212,053	211,337	211,931	182,898
Effect of common stock equivalents under incentive plans	23	637	—	952
Diluted weighted average shares outstanding	212,076	211,974	211,931	183,850

Segment Information (Tables)

9 Months Ended

Sep. 30, 2012

Segment Reporting [Abstract]

Schedule Of Operating Segment Results



	PRB			APP			WBIT			Other Operating Segments			Corporate, Other and Eliminations			Consolidated
	(in thousands)
Three Months Ended September 30, 2012
Revenues	$	406,719		$	436,409		$	217,963		$	26,527		$	—		$	1,087,618
Income (loss) from operations	38,873			88,695			40,828			(1,298		)	(31,138		)	135,960
Depreciation, depletion and amortization	43,944			61,596			17,881			2,594			823			126,838
Amortization of acquired sales contracts, net	(589		)	(3,711		)	—			207			—			(4,093		)
Mine closure and asset impairment costs	—			(1,801		)	(50		)	(210		)	(133		)	(2,194		)
Capital expenditures	5,620			77,772			13,510			3,640			1,353			101,895
Three Months Ended September 30, 2011
Revenues	$	394,012		$	611,403		$	168,795		$	24,463		$	—		$	1,198,673
Income (loss) from operations	38,632			63,350			24,653			(1,487		)	(48,892		)	76,256
Depreciation, depletion and amortization	42,676			73,420			19,125			3,674			652			139,547
Amortization of acquired sales contracts, net	3,802			(15,701		)	—			(832		)	33			(12,698		)



Mine closure and asset impairment costs	—			—			—		—			—			—
Capital expenditures	20,937			62,121			16,110		4,705			4,300			108,173
Nine Months Ended September 30, 2012
Revenues	$	1,130,408		$	1,409,776		$	562,074	$	88,549		$	—		$	3,190,807
Income (loss) from operations	94,163			(388,563		)	85,848		(3,757		)	(186,634		)	(398,943		)
Depreciation, depletion and amortization	122,298			210,789			54,935		9,704			1,946			399,672
Amortization of acquired sales contracts, net	(1,374		)	(21,658		)	—		471			—			(22,561		)
Mine closure and asset impairment costs	—			524,115			129		(437		)	(239		)	523,568
Total assets	2,234,941			3,846,136			676,057		454,118			2,724,602			9,935,854
Capital expenditures	15,399			222,177			42,761		8,153			15,478			303,968
Nine Months Ended September 30, 2011
Revenues	$	1,178,537		$	1,336,581		$	513,388	$	28,633		$	—		$	3,057,139
Income (loss) from operations	121,118			205,701			95,217		(1,412		)	(146,776		)	273,848
Depreciation, depletion and amortization	125,532			127,526			61,753		4,210			1,299			320,320
Amortization of acquired sales contracts, net	15,349			(19,907		)	—		(934		)	—			(5,492		)
Mine closure and asset impairment costs	—			7,316			—		—			—			7,316
Total assets	2,240,458			5,241,004			667,658		452,491			1,360,046			9,961,657
Capital expenditures	39,422			108,711			38,003		9,078			20,685			215,899

Reconciliation Statement Of Segment Income From Operations To Consolidated Income Before Income Taxes

A reconciliation of segment income from operations to consolidated income before income taxes follows:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
	(in thousands)
Income (loss) from operations	$	135,960		$	76,256		$	(398,943	)	$	273,848
Interest expense	(75,710		)	(77,694		)	(229,210		)	(154,523		)
Interest income	1,459			840			3,568			2,341
Other nonoperating expense	—			(1,708		)	(19,042		)	(51,448		)
Income (loss) before income taxes	$	61,709		$	(2,306	)	$	(643,627	)	$	70,218

- Definition

Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

+ References + Details

Supplemental Condensed Consolidating Financial Information (Tables)

9 Months Ended

Sep. 30, 2012

Supplemental Condensed Consolidating Financial Information [Abstract]

Schedule Of Condensed Consolidating Statements Of Operations

Condensed Consolidating Statements of Operations

Three Months Ended September 30, 2012



	Parent/Issuer			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Revenues	$	—		$	1,087,618		$	—		$	—		$	1,087,618
Costs, expenses and other
Cost of sales	2,434			922,455			—			(28,080		)	896,809
Depreciation, depletion and amortization	1,400			125,429			9			—			126,838
Amortization of acquired sales contracts, net	—			(4,093		)	—			—			(4,093		)
Legal contingencies	—			(79,532		)	—			—			(79,532		)
Mine closure and asset impairment costs	—			(2,194		)	—			—			(2,194		)
Goodwill impairment	—			—			—			—			—
Selling, general and administrative expenses	22,050			11,353			1,783			(1,920		)	33,266
Change in fair value of coal derivatives and coal trading activities, net	—			5,840			—			—			5,840
Other operating (income) expense, net	(11,051		)	(44,137		)	(89		)	30,001			(25,276		)
	14,833			935,121			1,703			1			951,658
Income from investment in subsidiaries	159,653			—			—			(159,653		)	—
Income (loss) from operations	144,820			152,497			(1,703		)	(159,654		)	135,960
Interest expense, net:
Interest expense	(91,589		)	(7,021		)	(649		)	23,549			(75,710		)
Interest income	8,478			14,584			1,946			(23,549		)	1,459
	(83,111		)	7,563			1,297			—			(74,251		)
Other non-operating expense
Bridge financing costs related to ICG	—			—			—			—			—
Net loss resulting from early retirement of ICG debt	—			—			—			—			—
	—			—			—			—			—
Income (loss) before income taxes	61,709			160,060			(406		)	(159,654		)	61,709
Provision for income taxes	15,958			—			—			—			15,958
Net income (loss)	45,751			160,060			(406		)	(159,654		)	45,751
Less: Net income attributable to noncontrolling interest	—			—			—			—			—
Net income (loss) attributable to Arch Coal, Inc.	$	45,751		$	160,060		$	(406	)	$	(159,654	)	$	45,751
Total comprehensive income (loss)	$	45,494		$	158,864		$	(406	)	$	(159,653	)	$	44,299

Condensed Consolidating Statements of Operations

Nine Months Ended September 30, 2012



	Parent/Issuer			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Revenues	$	—		$	3,190,807		$	—		$	—		$	3,190,807
Costs, expenses and other
Cost of sales	7,691			2,696,114			—			(74,866		)	2,628,939
Depreciation, depletion and amortization	3,960			395,688			24			—			399,672
Amortization of acquired sales contracts, net	—			(22,561		)	—			—			(22,561		)
Legal contingencies	—			(79,532		)	—			—			(79,532		)
Mine closure and asset impairment costs	—			523,568			—			—			523,568
Goodwill impairment	—			115,791			—			—			115,791
Selling, general and administrative expenses	62,468			36,388			5,871			(5,422		)	99,305
Change in fair value of coal derivatives and coal trading activities, net	—			(29,827		)	—			—			(29,827		)
Other operating (income) expense, net	(7,692		)	(105,753		)	(12,449		)	80,289			(45,605		)
	66,427			3,529,876			(6,554		)	1			3,589,750
Income from investment in subsidiaries	(316,041		)	—			—			316,041			—
Income (loss) from operations	(382,468		)	(339,069		)	6,554			316,040			(398,943		)
Interest expense, net:
Interest expense	(263,428		)	(27,815		)	(2,382		)	64,415			(229,210		)
Interest income	19,615			42,557			5,811			(64,415		)	3,568
	(243,813		)	14,742			3,429			—			(225,642		)
Other non-operating expense
Bridge financing costs related to ICG	—			—			—			—			—
Net loss resulting from early retirement of debt	(17,349		)	(1,693		)	—			—			(19,042		)
	(17,349		)	(1,693		)	—			—			(19,042		)
Income (loss) before income taxes	(643,630		)	(326,020		)	9,983			316,040			(643,627		)
Benefit from income taxes	(256,944		)	—			1,581			—			(255,363		)
Net income (loss)	(386,686		)	(326,020		)	8,402			316,040			(388,264		)
Less: Net income attributable to noncontrolling interest	(268		)	—			—			—			(268		)
Net income (loss) attributable to Arch Coal, Inc.	$	(386,954	)	$	(326,020	)	$	8,402		$	316,040		$	(388,532	)
Total comprehensive income (loss)	$	(385,185	)	$	(324,785	)	$	8,402		$	316,044		$	(385,524	)

Condensed Consolidating Statements of Operations

Three Months Ended September 30, 2011



	Parent/Issuer			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Revenues	$	—		$	1,198,673		$	—		$	—		$	1,198,673
Costs, expenses and other
Cost of sales	7,439			971,319			—			(25,908		)	952,850
Depreciation, depletion and amortization	720			138,827			—			—			139,547
Amortization of acquired sales contracts, net	—			(12,698		)	—			—			(12,698		)
Mine closure and asset impairment costs	—			—			—			—			—
Goodwill impairment	—			—			—			—			—
Selling, general and administrative expenses	20,261			13,752			1,058			(1,796		)	33,275
Change in fair value of coal derivatives and coal trading activities, net	—			8,360			—			—			8,360
Acquisition and transition costs related to ICG	4,694			—			—			—			4,694
Other operating (income) expense, net	(6,062		)	(25,314		)	61			27,704			(3,611		)
	27,052			1,094,246			1,119			—			1,122,417
Income from investment in subsidiaries	105,198			—			—			(105,198		)	—
Income (loss) from operations	78,146			104,427			(1,119		)	(105,198		)	76,256
Interest expense, net:
Interest expense	(84,044		)	(11,060		)	(541		)	17,951			(77,694		)
Interest income	3,592			14,023			1,176			(17,951		)	840
	(80,452		)	2,963			635			—			(76,854		)
Other non-operating expense
Bridge financing costs related to ICG	—			—			—			—			—
Net loss resulting from early retirement of debt	—			(1,708		)	—			—			(1,708		)
	—			(1,708		)	—			—			(1,708		)
Income (loss) before income taxes	(2,306		)	105,682			(484		)	(105,198		)	(2,306		)
Benefit from income taxes	(11,427		)	—			—			—			(11,427		)
Net income (loss)	9,121			105,682			(484		)	(105,198		)	9,121
Less: Net income attributable to noncontrolling interest	(231		)	—			—			—			(231		)
Net income (loss) attributable to Arch Coal, Inc.	$	8,890		$	105,682		$	(484	)	$	(105,198	)	$	8,890
Total comprehensive income (loss)	$	6,119		$	101,255		$	(484	)	$	(105,198	)	$	1,692

Condensed Consolidating Statements of Operations

Nine Months Ended September 30, 2011



	Parent/Issuer			Guarantor Subsidiaries			Non- Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Revenue	$	—		$	3,057,139		$	—		$	—		$	3,057,139
Costs, expenses and other
Cost of sales	15,658			2,382,406			—			(75,940		)	2,322,124
Depreciation, depletion and amortization	2,051			318,269			—			—			320,320
Amortization of acquired sales contracts, net	—			(5,492		)	—			—			(5,492		)
Mine closure and asset impairment costs	—			7,316			—			—			7,316
Goodwill impairment	—			—			—			—			—
Selling, general and administrative expenses	59,197			36,441			2,439			(5,328		)	92,749
Change in fair value of coal derivatives and coal trading activities, net	—			9,248			—			—			9,248
Acquisition and transition costs related to ICG	46,044			—			—			—			46,044
Other operating (income) expense, net	(15,460		)	(74,928		)	102			81,268			(9,018		)
	107,490			2,673,260			2,541			—			2,783,291
Income from investment in subsidiaries	388,253			—			—			(388,253		)	—
Income (loss) from operations	280,763			383,879			(2,541		)	(388,253		)	273,848
Interest expense, net:
Interest expense	(172,699		)	(34,858		)	(1,535		)	54,569			(154,523		)
Interest income	11,644			40,576			4,690			(54,569		)	2,341
	(161,055		)	5,718			3,155			—			(152,182		)
Other non-operating expense
Bridge financing costs related to ICG	(49,490		)	—			—			—			(49,490		)
Net loss resulting from early retirement of debt	—			(1,958		)	—			—			(1,958		)
	(49,490		)	(1,958		)	—			—			(51,448		)
Income (loss) before income taxes	70,218			387,639			614			(388,253		)	70,218
Benefit from income taxes	(1,407		)	—			—			—			(1,407		)
Net income (loss)	71,625			387,639			614			(388,253		)	71,625
Less: Net income attributable to noncontrolling interest	(822		)	—			—			—			(822		)
Net income (loss) attributable to Arch Coal, Inc.	$	70,803		$	387,639		$	614		$	(388,253	)	$	70,803
Total comprehensive income (loss)	$	72,511		$	379,390		$	614		$	(388,253	)	$	64,262

Schedule Of Condensed Consolidating Balance Sheets

Condensed Consolidating Balance Sheets

September 30, 2012



	Parent/Issuer			Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Assets
Cash and cash equivalents	$	313,548		$	225,431	$	11,777		$	—		$	550,756
Restricted cash	3,450			—		—			—			3,450
Short term investments	99,359			—		—			—			99,359
Receivables	52,081			24,672		276,992			(4,997		)	348,748
Inventories	—			391,526		—			—			391,526
Other	104,507			80,901		439			—			185,847
Total current assets	572,945			722,530		289,208			(4,997		)	1,579,686

Property, plant and equipment, net	28,622			7,343,360		81			—			7,372,063

Investment in subsidiaries	8,503,465			—		—			(8,503,465		)	—
Intercompany receivables	(1,399,215		)	1,561,073		(161,858		)	—			—
Note receivable from Arch Western	675,000			—		—			(675,000		)	—
Other	184,982			799,033		90			—			984,105
Total other assets	7,964,232			2,360,106		(161,768		)	(9,178,465		)	984,105
Total assets	$	8,565,799		$	10,425,996	$	127,521		$	(9,183,462	)	$	9,935,854

Liabilities and Stockholders’ Equity
Accounts payable	$	35,157		$	269,203	$	82		$	—		$	304,442
Accrued expenses and other current liabilities	92,337			269,834		1,772			(4,997		)	358,946
Current maturities of debt and short-term borrowings	14,832			863		100,000			—			115,695
Total current liabilities	142,326			539,900		101,854			(4,997		)	779,083
Long-term debt	4,463,386			2,059		—			0			4,465,445
Note payable to Arch Coal	—			675,000		—			(675,000		)	—
Asset retirement obligations	790			425,254		—			—			426,044
Accrued pension benefits	21,125			24,035		—			—			45,160
Accrued postretirement benefits other than pension	11,733			29,328		—			—			41,061
Accrued workers’ compensation	28,129			57,122		—			—			85,251
Deferred income taxes	665,414			80,665		—			—			746,079
Other noncurrent liabilities	67,629			114,557		278			—			182,464
Total liabilities	5,400,532			1,947,920		102,132			(679,997		)	6,770,587
Redeemable noncontrolling interest	—			—		—			—			—
Stockholders’ equity	3,165,267			8,478,076		25,389			(8,503,465		)	3,165,267
Total liabilities and stockholders’ equity	$	8,565,799		$	10,425,996	$	127,521		$	(9,183,462	)	$	9,935,854

Condensed Consolidating Balance Sheets

December 31, 2011



	Parent/Issuer			Guarantor Subsidiaries		Non-Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Assets
Cash and cash equivalents	$	61,375		$	75,425	$	1,349		$	—		$	138,149
Restricted cash	10,322			—		—			—			10,322
Receivables	65,187			27,001		378,608			(1,617		)	469,179
Inventories	—			377,490		—			—			377,490
Other	81,732			105,282		620			—			187,634
Total current assets	218,616			585,198		380,577			(1,617		)	1,182,774

Property, plant and equipment, net	21,241			7,918,816		9,093			—			7,949,150

Investment in subsidiaries	8,805,731			—		—			(8,805,731		)	—
Intercompany receivables	(1,457,864		)	1,716,424		(258,560		)	—			—
Note receivable from Arch Western	225,000			—		—			(225,000		)	—
Other	184,266			897,567		202			—			1,082,035
Total other assets	7,757,133			2,613,991		(258,358		)	(9,030,731		)	1,082,035
Total assets	$	7,996,990		$	11,118,005	$	131,312		$	(9,032,348	)	$	10,213,959

Liabilities and Stockholders’ Equity
Accounts payable	$	25,409		$	358,347	$	26		$	—		$	383,782
Accrued expenses and other current liabilities	75,133			282,434		85			(1,617		)	356,035
Current maturities of debt and short-term borrowings	172,564			1,987		106,300			—			280,851
Total current liabilities	273,106			642,768		106,411			(1,617		)	1,020,668
Long-term debt	3,308,674			453,623		—			0			3,762,297
Note payable to Arch Coal	—			225,000		—			(225,000		)	—
Asset retirement obligations	877			445,907		—			—			446,784
Accrued pension benefits	19,198			29,046		—			—			48,244
Accrued postretirement benefits other than pension	13,843			28,466		—			—			42,309
Accrued workers’ compensation	17,272			54,676		—			—			71,948
Deferred income taxes	621,483			355,270		—			—			976,753
Other noncurrent liabilities	152,963			102,335		84			—			255,382
Total liabilities	4,407,416			2,337,091		106,495			(226,617		)	6,624,385
Redeemable noncontrolling interest	11,534			—		—			—			11,534
Stockholders’ equity	3,578,040			8,780,914		24,817			(8,805,731		)	3,578,040
Total liabilities and stockholders’ equity	$	7,996,990		$	11,118,005	$	131,312		$	(9,032,348	)	$	10,213,959

Schedule Of Condensed Consolidating Statements Of Cash Flows

Condensed Consolidating Statements of Cash Flows

Nine Months Ended September 30, 2012



	Parent/Issuer			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Cash provided by (used in) operating activities	$	(500,331	)	$	771,047		$	85,679		$	—		$	356,395
Investing Activities
Change in restricted cash	6,872			—			—			—			6,872
Capital expenditures	(4,150		)	(299,818		)	—			—			(303,968		)
Proceeds from dispositions of property, plant and equipment	—			1,127			21,497			—			22,624
Investments in and advances to affiliates	(5,138		)	(9,082		)	—			1,535			(12,685		)
Purchases of short term investments	(99,628		)	—			—			—			(99,628		)
Purchase of noncontrolling interest	(17,500		)	—			—			—			(17,500		)
Additions to prepaid royalties	—			(9,192		)	—			—			(9,192		)
Cash used in investing activities	(119,544		)	(316,965		)	21,497			1,535			(413,477		)
Financing Activities
Contributions from parent	—			1,535						(1,535		)	—
Proceeds from term note	1,386,000			—			—			—			1,386,000
Payments to retire debt	—			(452,806		)	—			—			(452,806		)
Net decrease in borrowings under lines of credit and commercial paper program	(381,300		)	—			—			—			(381,300		)
Payments on term note	(3,500		)	—			—			—			(3,500		)
Net payments on other debt	(13,078		)	—			—			—			(13,078		)
Debt financing costs	(34,640		)	—			(46		)	—			(34,686		)
Dividends paid	(36,072		)	—			—			—			(36,072		)
Issuance of common stock under incentive plans	5,131			—			—			—			5,131
Transactions with affiliates, net	(50,493		)	147,195			(96,702		)	—			—
Cash provided by (used in) financing activities	872,048			(304,076		)	(96,748		)	(1,535		)	469,689
Increase in cash and cash equivalents	252,173			150,006			10,428			—			412,607
Cash and cash equivalents, beginning of period	61,375			75,425			1,349			—			138,149
Cash and cash equivalents, end of period	$	313,548		$	225,431		$	11,777		$	—		$	550,756

Condensed Consolidating Statements of Cash Flows

Nine Months Ended September 30, 2011



	Parent/Issuer			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated
	(In thousands)
Cash provided by (used in) operating activities	$	(444,664	)	$	896,941		$	19,090		$	—		$	471,367
Investing Activities
Acquisition of ICG, net of cash acquired	(2,894,339		)	—			—			—			(2,894,339		)
Change in restricted cash	(5,939		)	—			—			—			(5,939		)
Capital expenditures	(5,137		)	(210,660		)	(102		)	—			(215,899		)
Proceeds from dispositions of property, plant and equipment	—			25,133			—			—			25,133
Investments in and advances to affiliates	(777,341		)	(29,872		)	—			750,386			(56,827		)
Additions to prepaid royalties	—			(26,135		)	—			—			(26,135		)
Cash used in investing activities	(3,682,756		)	(241,534		)	(102		)	750,386			(3,174,006		)
Financing Activities
Proceeds from the issuance of senior notes	2,000,000			—			—			—			2,000,000
Proceeds from the issuance of common stock, net	1,267,776			—			—			—			1,267,776
Contributions from parent	—			750,386			—			(750,386		)	—
Payments to retire debt	—			(604,096		)	—			—			(604,096		)
Net decrease in borrowings under lines of credit and commercial paper program	340,000			(56,904		)	—			—			283,096
Net payments on other debt	(8,792		)	—			—			—			(8,792		)
Debt financing costs	(114,563		)	(16		)	(8		)	—			(114,587		)
Dividends paid	(57,470		)	—			—			—			(57,470		)
Issuance of common stock under incentive plans	1,628			—			—			—			1,628
Transactions with affiliates, net	742,906			(724,238		)	(18,668		)	—			—
Cash provided by (used in) financing activities	4,171,485			(634,868		)	(18,676		)	(750,386		)	2,767,555
Increase in cash and cash equivalents	44,065			20,539			312			—			64,916
Cash and cash equivalents, beginning of period	13,713			79,880			—			—			93,593
Cash and cash equivalents, end of period	$	57,778		$	100,419		$	312		$	—		$	158,509

Basis Of Presentation (Narrative) (Details) $ in Millions	6 Months Ended	9 Months Ended
Basis Of Presentation (Narrative) (Details) $ in Millions	Jul. 02, 2012 USD ($)	Sep. 30, 2012	Apr. 09, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of mining complexes operated		15
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			0.50%
Payments for Repurchase of Redeemable Noncontrolling Interest	$ 17.5

Debt (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Debt (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	May 30, 2012	May 16, 2012	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 600,000		$ 600,000				$ 2,000,000
Proceeds from Issuance of Long-term Debt			1,386,000
Net loss resulting from early retirement of debt and refinancing activities		$ 1,708	19,042	1,958
Deferred finance costs	27,400		27,400
Remaining borrowing capacity	366,000		366,000
Cash and cash equivalents	550,756	$ 158,509	550,756	$ 158,509				$ 138,149	$ 93,593
6.75% Senior Notes Due 2013 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 450,000		$ 450,000
Stated interest rate	6.75%		6.75%
Debt Instrument, Repurchased Face Amount	$ 304,000		$ 304,000
Debt instrument, repurchase amount					$ 146,000	$ 304,800
Write off of deferred debt issuance cost			(1,100)
Loss on extinguishment of debt other than deferred debt issuance costs			800
Loans Payable [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,400,000		$ 1,400,000
Debt instrument, maturity period			6 years
Debt instrument, discount (premium), percentage			1.00%
Debt instrument, periodic principal payment			$ 3,500
Frequency of periodic payment			Quarterly
Basis spread on variable rate	4.50%		4.50%
Line of Credit [Member]
Debt Instrument [Line Items]
Write off of deferred debt issuance cost			$ (17,300)
Deferred finance costs	$ 24,800		$ 24,800
Maximum [Member] \| 6.75% Senior Notes Due 2013 [Member]
Debt Instrument [Line Items]
Tender offer, offering price per unit of principal	1,002.50		1,002.50
Minimum [Member] \| Loans Payable [Member]
Debt Instrument [Line Items]
Stated interest rate	1.25%		1.25%

Debt (Debt) (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Indebtedness to banks under credit facilities	$ 100,000	$ 481,300
Other	7,290	21,903
Total	4,581,140	4,043,148
Less current maturities of debt and short-term borrowings	115,695	280,851
Long-term debt	$ 4,465,445	3,762,297
6.75% Senior Notes Due 2013 [Member]
Debt Instrument [Line Items]
Senior notes		450,971
Senior notes interest rate	6.75%
Debt Instrument, Face Amount	$ 450,000
8.75% Senior Notes Due 2016 [Member]
Debt Instrument [Line Items]
Senior notes	$ 590,475	588,974
Senior notes interest rate	8.75%
Debt Instrument, Face Amount	$ 600,000
7.00% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes	$ 1,000,000	1,000,000
Senior notes interest rate	7.00%
7.25% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Senior notes	$ 500,000	500,000
Senior notes interest rate	7.25%
7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Senior notes	$ 1,000,000	$ 1,000,000
Senior notes interest rate	7.25%
Loans Payable [Member]
Debt Instrument [Line Items]
Term loan ($1.4 billion face value) due 2018	$ 1,383,375
Debt Instrument, Face Amount	$ 1,400,000
Debt Instrument, Basis Spread on Variable Rate	4.50%

Mine Closure and Asset Impairment Costs (Narrative) (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2012 USD ($)	Sep. 30, 2012 USD ($) mining_complex
Restructuring and Related Activities [Abstract]
number of mining complexes temporarily idled \| mining_complex		1
number of mining complexes closed \| mining_complex		4
Long-Lived Assets to be Abandoned, Carrying Value of Asset \| $	$ 51,000	$ 51,000
Curtailments \| $	$ (2,200)	$ (1,770)
Restructuring and Related Cost, Number of Positions Eliminated		750

- Definition

The amount of decrease that is related to an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(10)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Plan Curtailment
-URI http://asc.fasb.org/extlink&oid=6520938

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 15
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=7577095&loc=d3e8001-114927

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 88
-Paragraph 6
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Mine Closure and Asset Impairment Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Restructuring and Related Activities [Abstract]
Parts and supplies inventory writedown			$ 2,598
Impairment of property, plant and equipment			95,641
Impairment of coal properties and deferred development costs			403,279
Royalty obligations			11,546
Employee termination benefits			12,274
Curtailments	$ (2,200)		(1,770)
Mine closure and asset impairment costs	$ (2,194)		$ 523,568	$ 7,316

Charge to cost of goods sold that represents the reduction of the carrying amount of inventory, generally attributable to obsolescence or market conditions.

+ References + Details

- Definition

This element represents the payments that the lessee is obligated to make or can be required to make in connection with a property under the terms of an agreement classified as an operating lease, excluding contingent rentals and a guarantee by the lessee of the lessor's debt and the lessee's obligation to pay (apart from the rental payments) executory costs such as insurance, maintenance, and taxes.

+ References + Details

- Definition

The charge against earnings in the period for known and estimated costs of termination benefits provided to current employees that are involuntarily terminated under a benefit arrangement associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, excluding costs or losses pertaining to an entity newly acquired in a business combination or a discontinued operation as defined by generally accepted accounting principles and costs associated with one-time termination benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=6394695&loc=d3e140904-122747

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(10)
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
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-Paragraph 1
-Subparagraph (SAB TOPIC 5.P.3)
-URI http://asc.fasb.org/extlink&oid=6394695&loc=d3e140864-122747

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5-8
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section P
-Subsection 3, 4

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 146
-Paragraph 8-13, 20
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS146-1
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 112
-Paragraph 7
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Investments in Available-for-Sale Securities (Details) - USD ($)	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 104,899,000	$ 5,268,000
Available-for-sale Securities, Gross Unrealized Losses	4,678,000	4,394,000
Available-for-sale Securities, Gross Unrealized Losses	(2,783,000)	(2,122,000)
Available-for-sale Securities, Fair Value Disclosure	106,794,000	7,540,000
Available-for-sale Securities, Debt Securities, Current	99,359,000
US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	72,964,000
Available-for-sale Securities, Gross Unrealized Losses	0
Available-for-sale Securities, Gross Unrealized Losses	(157,000)
Available-for-sale Securities, Fair Value Disclosure	72,807,000
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	26,664,000
Available-for-sale Securities, Gross Unrealized Losses	0
Available-for-sale Securities, Gross Unrealized Losses	(112,000)
Available-for-sale Securities, Fair Value Disclosure	26,552,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	5,271,000	5,268,000
Available-for-sale Securities, Gross Unrealized Losses	4,678,000	4,394,000
Available-for-sale Securities, Gross Unrealized Losses	(2,514,000)	(2,122,000)
Available-for-sale Securities, Fair Value Disclosure	7,435,000	7,540,000
Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Financial Instruments, Owned, Corporate Debt, at Fair Value	26,552,000
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	72,807,000
Available-for-sale Securities, Debt Securities, Current	99,359,000
Other Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Equity Securities	$ 7,435,000	$ 7,540,000

Goodwill (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Goodwill (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Mar. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Goodwill	$ 480,312		$ 480,312			$ 596,103
Goodwill impairment			$ 115,791
Black Thunder [Member]
Goodwill [Line Items]
Goodwill					$ 115,800

- Definition

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph e
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 43
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 72
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
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-Subparagraph e
-Clause 1
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 68
-Subparagraph l
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 34
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13854-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 230
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 43
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
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-Subparagraph e
-Clause 5
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 47
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Equity Investments And Membership Interests In Joint Ventures (Narrative) (Details) $ in Millions	Sep. 30, 2012 USD ($)
Equity Method Investments and Joint Ventures [Abstract]
Future development costs, maximum limit	$ 72.9

Equity Investments And Membership Interests In Joint Ventures (Schedule Of Equity Method Investments) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at December 31, 2011	$ 225,605
Investments in affiliates
Advances to (distributions from) affiliates, net	5,449
Equity in comprehensive income (loss)	6,591
Balance at September 30, 2012	237,645
Notes receivable from investees: Balance at December 31, 2011	41,478	$ 35,810
Notes receivable from investees: Balance at September 30, 2012	41,478	35,810
Knight Hawk [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at December 31, 2011	135,225
Investments in affiliates
Advances to (distributions from) affiliates, net	(5,342)
Equity in comprehensive income (loss)	16,033
Balance at September 30, 2012	145,916
Notes receivable from investees: Balance at December 31, 2011
Notes receivable from investees: Balance at September 30, 2012
DKRW [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at December 31, 2011	19,715
Investments in affiliates
Advances to (distributions from) affiliates, net
Equity in comprehensive income (loss)	(3,457)
Balance at September 30, 2012	16,258
Notes receivable from investees: Balance at December 31, 2011	36,402	30,751
Notes receivable from investees: Balance at September 30, 2012	36,402	30,751
DTA [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at December 31, 2011	16,086
Investments in affiliates
Advances to (distributions from) affiliates, net	3,230
Equity in comprehensive income (loss)	(3,625)
Balance at September 30, 2012	15,691
Notes receivable from investees: Balance at December 31, 2011
Notes receivable from investees: Balance at September 30, 2012
Tenaska [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at December 31, 2011	15,266
Investments in affiliates
Advances to (distributions from) affiliates, net
Equity in comprehensive income (loss)	(2)
Balance at September 30, 2012	15,264
Notes receivable from investees: Balance at December 31, 2011	5,076	5,059
Notes receivable from investees: Balance at September 30, 2012	5,076	5,059
Millennium [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at December 31, 2011	26,324
Investments in affiliates
Advances to (distributions from) affiliates, net	5,853
Equity in comprehensive income (loss)	(2,358)
Balance at September 30, 2012	29,819
Notes receivable from investees: Balance at December 31, 2011
Notes receivable from investees: Balance at September 30, 2012
Tongue River [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Balance at December 31, 2011	12,989
Investments in affiliates
Advances to (distributions from) affiliates, net	1,708
Equity in comprehensive income (loss)
Balance at September 30, 2012	14,697
Notes receivable from investees: Balance at December 31, 2011
Notes receivable from investees: Balance at September 30, 2012

Derivatives (Narrative) (Details) gal in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2012 USD ($)	Sep. 30, 2011 USD ($)	Sep. 30, 2012 USD ($) gal	Sep. 30, 2011 USD ($)	Dec. 31, 2011 USD ($)
Derivative [Line Items]
Gain (Loss) on Components Excluded from Assessment of Price Risk Hedge Effectiveness			$ 8.2
Gain (loss) on components excluded from assessment of price risk hedge effectiveness, net of tax			5.2
Current asset for the right to reclaim cash collateral					$ 12.4
Current liability for the obligation to post cash collateral	$ 7.4		7.4
Net unrealized and realized gains (losses) related to trading portfolio	5.5	$ (2.2)	6.2	$ (1.7)
Gain on derivative contracts designated as hedge instruments in cash flow hedges to be reclassified from OCI into earnings during the next twelve months	$ 4.0		$ 4.0
Minimum Purchase [Member]
Derivative [Line Items]
Gallons of diesel fuel purchased annually \| gal			73
Maximum Purchase [Member]
Derivative [Line Items]
Gallons of diesel fuel purchased annually \| gal			78
Year One [Member]
Derivative [Line Items]
Percent of diesel purchases hedged	80.00%		80.00%
Value of trading portfolio realized			$ 3.6
Year Two [Member]
Derivative [Line Items]
Percent of diesel purchases hedged	67.00%		67.00%
Value of trading portfolio realized			$ (1.6)
Heating Oil-Diesel Purchases [Member]
Derivative [Line Items]
Quantities under derivative contracts	63,500,000		63,500,000
Heating Oil-Fuel Surchages [Member]
Derivative [Line Items]
Quantities under derivative contracts	14,000,000		14,000,000

Derivatives (Schedule of Price Risk Derivatives) (Details) number in Thousands	Sep. 30, 2012
Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	13,368
Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	3,891
Year One [Member] \| Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	2,915
Year One [Member] \| Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	1,851
Year Two [Member] \| Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	5,713
Year Two [Member] \| Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	1,140
Year Three [Member] \| Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	4,020
Year Three [Member] \| Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	900
Year Four [Member] \| Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	720
Year Four [Member] \| Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held

Derivatives (Disclosure Of Fair Value Of Derivatives) (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Derivative [Line Items]
Derivative Assets	$ 91,190	$ 42,263
Derivative Liabilities	(40,156)	(25,962)
Effect of counterparty netting in derivative assets	(36,658)	(18,134)
Effect of counterparty netting in derivative liabilities	36,658	18,134
Net derivative assets as classified in the balance sheet	54,532	24,129
Net derivative liabilities as classified in the balance sheet	(3,498)	(7,828)
Net derivatives as classified in the balance sheet	51,034	16,301
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Assets	4,509	10,106
Derivative Liabilities	(1,679)
Designated as Hedging Instrument [Member] \| Coal [Member]
Derivative [Line Items]
Derivative Assets	4,509	1,109
Derivative Liabilities	(1,679)
Designated as Hedging Instrument [Member] \| Heating Oil-Diesel Purchases [Member]
Derivative [Line Items]
Derivative Assets		8,997
Derivative Liabilities
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Assets	86,681	32,157
Derivative Liabilities	(38,477)	(25,962)
Not Designated as Hedging Instrument [Member] \| Coal Held for Trading Purposes [Member]
Derivative [Line Items]
Derivative Assets	27,190	15,505
Derivative Liabilities	(25,171)	(19,927)
Not Designated as Hedging Instrument [Member] \| Coal [Member]
Derivative [Line Items]
Derivative Assets	45,739	14,855
Derivative Liabilities	(13,249)	(6,035)
Not Designated as Hedging Instrument [Member] \| Heating Oil-Diesel Purchases [Member]
Derivative [Line Items]
Derivative Assets	10,913
Derivative Liabilities	(57)
Not Designated as Hedging Instrument [Member] \| Heating Oil-Fuel Surchages [Member]
Derivative [Line Items]
Derivative Assets	2,839	1,797
Derivative Liabilities

Derivatives (Net Derivatives As Reflected On The Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 51,034	$ 16,301
Other Current Assets [Member] \| Heating Oil [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	13,695	10,794
Coal Derivative Assets [Member] \| Coal [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	40,837	13,335
Coal Derivative Liabilities [Member] \| Coal [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ (3,498)	$ (7,828)

Derivatives (Effects Of Derivatives On Measures Of Financial Performance) (Details) - USD ($)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2012

Sep. 30, 2011

Sep. 30, 2012

Sep. 30, 2011

Derivative Instruments, Gain (Loss) [Line Items]

Gain (Loss) Recognized in OCI (Effective Portion)

$ 81

$ (5,840)

$ 3,861

$ 4,052

Gains (Losses) Reclassified from OCI into Income (Effective Portion)

542

5,588

1,552

15,736

Coal Purchases [Member]

Derivative Instruments, Gain (Loss) [Line Items]

Gain (Loss) Recognized in OCI (Effective Portion)

^[1]

(178)

(1,274)

(1,122)

(2,053)

Gains (Losses) Reclassified from OCI into Income (Effective Portion)

^[1]

Coal Sales [Member]

Derivative Instruments, Gain (Loss) [Line Items]

Gain (Loss) Recognized in OCI (Effective Portion)

^[2]

259

1,820

4,983

4,570

Gains (Losses) Reclassified from OCI into Income (Effective Portion)

^[2]

542

466

1,552

790

Heating Oil-Diesel Purchases [Member]

Derivative Instruments, Gain (Loss) [Line Items]

Gain (Loss) Recognized in OCI (Effective Portion)

^[1]

(6,386)

1,535

Gains (Losses) Reclassified from OCI into Income (Effective Portion)

^[1]

5,122

14,946

Not Designated as Hedging Instrument [Member] | Coal [Member]

Derivative Instruments, Gain (Loss) [Line Items]

Gain (Loss) Recognized in OCI (Effective Portion)

^[3]

(11,328)

(6,131)

23,670

(7,550)

Realized Gains (Losses)

^[4]

14,072

166

25,901

313

Not Designated as Hedging Instrument [Member] | Heating Oil-Diesel Purchases [Member]

Derivative Instruments, Gain (Loss) [Line Items]

Realized Gains (Losses)

^[4]

5,184

(16,902)

Not Designated as Hedging Instrument [Member] | Heating Oil-Fuel Surchages [Member]

Derivative Instruments, Gain (Loss) [Line Items]

Realized Gains (Losses)

^[4]

$ 1,092

$ (2,501)

$ (1,140)

$ (2,501)

[1]	— Cost of sales
[2]	— Revenues
[3]	— Change in fair value of coal derivatives and coal trading activities, net
[4]	— Other operating income, net

Inventories (Inventories) (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Inventory Disclosure [Abstract]
Coal	$ 202,103	$ 206,517
Repair parts and supplies	178,710	163,527
Work-in-process	10,713	7,446
Inventories	391,526	377,490
Allowance for slow-moving and obsolete inventories	$ 11,400	$ 13,100

- Definition

The amount of the valuation account as of the balance sheet date which reduces the carrying amount of inventory to net realizable value; takes into consideration such factors as market value, excessive quantities based on expected sales, technological obsolescence, and shrinkage. May also provide for estimated product returns or price concessions pertaining to product cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.BB)
-URI http://asc.fasb.org/extlink&oid=6386940&loc=d3e100047-122729

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6386567&loc=d3e3927-108312

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Paragraph 14
-Chapter 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Paragraph 8, 9, 14
-Chapter 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Section A
-Paragraph 9
-Chapter 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 09
-Article 12

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 6
-Subparagraph a
-Article 5

+ Details

Fair Value Measurements (Summary Of Change In The Fair Values Of Financial Instruments Categorized As Level 3) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 5,109	$ 6,211
Realized and unrealized losses recognized in earnings, net	4,265	(7,331)
Purchases	2,869	14,598
Settlements	(134)	(1,369)
Ending balance	$ 12,109	$ 12,109

Fair Value Measurements (Narrative) (Details) $ in Millions	3 Months Ended	9 Months Ended
Fair Value Measurements (Narrative) (Details) $ in Millions	Sep. 30, 2012 USD ($)	Sep. 30, 2012 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net unrealized gains related to level 3 financial instruments	$ 4.3	$ (3.1)
Fair value of senior notes and other long-term debt, including amounts classified as current	$ 4,200.0	$ 4,200.0

Fair Value Measurements (Summary Of Financial Assets And Liabilities Accounted For At Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Assets:
Derivatives	$ 54,532	$ 24,129
Investments in equity securities	106,794	7,540
Liabilities:
Derivatives	3,498	$ 7,828
Total assets	161,326
Level 1 [Member]
Assets:
Derivatives	40,884
Investments in equity securities	58,109
Liabilities:
Derivatives
Total assets	98,993
Level 2 [Member]
Assets:
Derivatives	(47)
Investments in equity securities	48,685
Liabilities:
Derivatives	1,912
Total assets	48,638
Level 3 [Member]
Assets:
Derivatives	13,695
Investments in equity securities
Liabilities:
Derivatives	1,586
Total assets	$ 13,695

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References + Details

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References + Details

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References + Details

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011
Accrued Expenses and Other Current Liabilities [Abstract]
Payroll and employee benefits	$ 80,782	$ 65,323
Taxes other than income taxes	123,100	133,331
Interest	70,619	55,266
Coal supply agreement liability	16,327	38,441
Workers’ compensation	10,155	11,666
Asset retirement obligations	44,178	27,119
Other	10,287	17,061
Accrued Liabilities, Current	$ 355,448	$ 348,207

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable for real and property taxes. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References + Details

- Definition

Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References + Details

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References + Details

Stock-Based Compensation And Other Incentive Plans (Narrative) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options issued during period	1,300,000
Weighted average exercise price of options granted	$ 13.30
Options granted, weighted average grant date fair value	$ 5.27
Option, weighted average risk free rate	0.75706%
Option, weighted average dividend yield	2.92%
Option, weighted average volatility	60.72%
Amounts unpaid under long term incentive plan	$ 11,800,000	$ 9,600,000
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of options (Years)	4 years 6 months
Share based awards vesting period	3 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based awards vesting period	3 years
Stock Issued During Period, Shares, Restricted Stock Award, Gross	569,550
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 13.32

Workers' Compensation Expense (Worker's Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Defined Benefit Plan Disclosure [Line Items]
Curtailments	$ (2,200)		$ (1,770)
Workers' Compensation [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	419	$ 807	1,458	$ 1,246
Interest cost	629	619	1,708	1,177
Net amortization		(109)	(574)	(370)
Curtailments			1,933
Net benefit cost (credit)	1,048	1,317	4,525	2,053
Traumatic injury claims and assessments	7,453	5,207	19,052	10,856
Total workers' compensation expense	$ 8,501	$ 6,524	$ 23,577	$ 12,909

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References + Details

- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Service Cost (Component of Net Periodic Pension Cost)
-URI http://asc.fasb.org/extlink&oid=6525008

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph a, h
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Employee Benefit Plans (Pension And Other Postretirement Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Defined Benefit Plan Disclosure [Line Items]
Curtailments	$ (2,200)		$ (1,770)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6,156	$ 4,122	21,062	$ 12,367
Interest cost	3,683	4,063	11,755	12,190
Curtailments			324
Expected return on plan assets	(5,508)	(5,453)	(16,523)	(16,359)
Amortization of prior service cost (credit)	273	(47)	200	(142)
Amortization of other actuarial (gains) losses	3,248	2,187	11,019	6,561
Net benefit cost (credit)	7,852	4,872	27,837	14,617
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	541	1,493	1,629	2,416
Interest cost	508	1,125	1,519	2,152
Curtailments	(2,212)	0	(4,049)	0
Amortization of prior service cost (credit)	(2,837)	(636)	(8,708)	(1,773)
Amortization of other actuarial (gains) losses	(130)	(775)	(391)	(2,325)
Net benefit cost (credit)	$ (4,130)	$ 1,207	$ (10,000)	$ 470

Earnings Per Common Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Line Items]
Basic, weighted average shares outstanding	212,053	211,337	211,931	182,898
Effect of common stock equivalents under incentive plans	23	637		952
Diluted weighted average shares outstanding	212,076	211,974	211,931	183,850
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	5,800	3,000	5,000	2,100

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Antidilution
-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Diluted Earnings Per Share
-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Contingent Stock Agreement
-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 13, 14
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References + Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1448-109256

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Weighted-Average Number of Common Shares Outstanding
-URI http://asc.fasb.org/extlink&oid=6528421

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 8
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Guarantees (Narrative) (Details) $ in Millions	Sep. 30, 2012 USD ($)
Guarantees [Abstract]
Letters of credit posted in the Company's favor	$ 16.7
Guarantee obligations, maximum exposure, undiscounted	35.3
Supply Commitment, Remaining Minimum Amount Committed	$ 64.0

Contingencies (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
Contingencies (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2012	Dec. 31, 2011	Aug. 25, 2011	Aug. 13, 2007
Purchase replacement coal				$ 100.0
Damages and interest awarded			$ 104.1
Appeal Bond	$ 124.9
Amount accrued	32.3	$ 117.2
Amount accrued current portion	4.3	$ 6.3
Maximum [Member]
Aggregate amount of past and future damages	377.0
Minimum [Member]
Aggregate amount of past and future damages	$ 228.0

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14557-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 11
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 12
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Segment Information (Narrative) (Details)	9 Months Ended
Segment Information (Narrative) (Details)	Sep. 30, 2012 Segment
Segment Reporting [Abstract]
Segment Reporting, Factors Used to Identify Entity's Reportable Segments	3

Segment Information (Schedule Of Operating Segment Results) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	$ 1,087,618	$ 1,198,673	$ 3,190,807	$ 3,057,139
Income (loss) from operations	135,960	76,256	(398,943)	273,848
Depreciation, depletion and amortization	126,838	139,547	399,672	320,320
Amortization of acquired sales contacts, net	(4,093)	(12,698)	(22,561)	(5,492)
Mine closure and asset impairment costs	(2,194)		523,568	7,316
Total assets	9,935,854	9,961,657	9,935,854	9,961,657	$ 10,213,959
Capital expenditures	101,895	108,173	303,968	215,899
PRB [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	406,719	394,012	1,130,408	1,178,537
Income (loss) from operations	38,873	38,632	94,163	121,118
Depreciation, depletion and amortization	43,944	42,676	122,298	125,532
Amortization of acquired sales contacts, net	(589)	3,802	(1,374)	15,349
Mine closure and asset impairment costs			0
Total assets	2,234,941	2,240,458	2,234,941	2,240,458
Capital expenditures	5,620	20,937	15,399	39,422
APP [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	436,409	611,403	1,409,776	1,336,581
Income (loss) from operations	88,695	63,350	(388,563)	205,701
Depreciation, depletion and amortization	61,596	73,420	210,789	127,526
Amortization of acquired sales contacts, net	(3,711)	(15,701)	(21,658)	(19,907)
Mine closure and asset impairment costs	(1,801)		524,115	7,316
Total assets	3,846,136	5,241,004	3,846,136	5,241,004
Capital expenditures	77,772	62,121	222,177	108,711
WBIT [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	217,963	168,795	562,074	513,388
Income (loss) from operations	40,828	24,653	85,848	95,217
Depreciation, depletion and amortization	17,881	19,125	54,935	61,753
Amortization of acquired sales contacts, net
Mine closure and asset impairment costs	(50)		129
Total assets	676,057	667,658	676,057	667,658
Capital expenditures	13,510	16,110	42,761	38,003
Other [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	26,527	24,463	88,549	28,633
Income (loss) from operations	(1,298)	(1,487)	(3,757)	(1,412)
Depreciation, depletion and amortization	2,594	3,674	9,704	4,210
Amortization of acquired sales contacts, net	207	(832)	471	(934)
Mine closure and asset impairment costs	(210)		(437)
Total assets	454,118	452,491	454,118	452,491
Capital expenditures	3,640	4,705	8,153	9,078
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue
Income (loss) from operations	(31,138)	(48,892)	(186,634)	(146,776)
Depreciation, depletion and amortization	823	652	1,946	1,299
Amortization of acquired sales contacts, net		33
Mine closure and asset impairment costs	(133)		(239)
Total assets	2,724,602	1,360,046	2,724,602	1,360,046
Capital expenditures	$ 1,353	$ 4,300	$ 15,478	$ 20,685

Segment Information (Reconciliation Statement Of Segment Income from Operations To Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting [Abstract]
Income (loss) from operations	$ 135,960	$ 76,256	$ (398,943)	$ 273,848
Interest expense	(75,710)	(77,694)	(229,210)	(154,523)
Interest income	1,459	840	3,568	2,341
Other nonoperating expenses		(1,708)	(19,042)	(51,448)
Income (loss) before income taxes	$ 61,709	$ (2,306)	$ (643,627)	$ 70,218

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Condensed Financial Statement Line Items
Revenues	$ 1,087,618	$ 1,198,673	$ 3,190,807	$ 3,057,139
Costs, expenses and other
Cost of sales	896,809	952,850	2,628,939	2,322,124
Depreciation, depletion and amortization	126,838	139,547	399,672	320,320
Amortization of acquired sales contracts, net	(4,093)	(12,698)	(22,561)	(5,492)
Legal contingencies	(79,532)		(79,532)
Mine closure and asset impairment costs	(2,194)		523,568	7,316
Goodwill impairment			115,791
Selling, general and administrative expenses	33,266	33,275	99,305	92,749
Change in fair value of coal derivatives and coal trading activities, net	5,840	8,360	(29,827)	9,248
Acquisition and transition costs related to ICG		4,694		46,044
Other operating (income) expense, net	(25,276)	(3,611)	(45,605)	(9,018)
Total operating expenses	951,658	1,122,417	3,589,750	2,783,291
Income from investment in subsidiaries
Income (loss) from operations	135,960	76,256	(398,943)	273,848
Interest expense, net:
Interest expense	(75,710)	(77,694)	(229,210)	(154,523)
Interest income	1,459	840	3,568	2,341
Interest expense, net	(74,251)	(76,854)	(225,642)	(152,182)
Other non-operating expense
Bridge financing costs related to ICG				(49,490)
Net loss resulting from early retirement and refinancing of debt		(1,708)	(19,042)	(1,958)
Other nonoperating expense, Total		(1,708)	(19,042)	(51,448)
Income (loss) before income taxes	61,709	(2,306)	(643,627)	70,218
Provision for (benefit from) income taxes	15,958	(11,427)	(255,363)	(1,407)
Net income (loss)	45,751	9,121	(388,264)	71,625
Less: Net income attributable to noncontrolling interest		(231)	(268)	(822)
Net income (loss) attributable to Arch Coal, Inc.	45,751	8,890	(388,532)	70,803
Total comprehensive income (loss)	44,299	1,692	(385,524)	64,262
Parent/Issuer [Member]
Condensed Financial Statement Line Items
Revenues
Costs, expenses and other
Cost of sales	2,434	7,439	7,691	15,658
Depreciation, depletion and amortization	1,400	720	3,960	2,051
Amortization of acquired sales contracts, net
Legal contingencies
Mine closure and asset impairment costs
Goodwill impairment
Selling, general and administrative expenses	22,050	20,261	62,468	59,197
Change in fair value of coal derivatives and coal trading activities, net
Acquisition and transition costs related to ICG		4,694		46,044
Other operating (income) expense, net	(11,051)	(6,062)	(7,692)	(15,460)
Total operating expenses	14,833	27,052	66,427	107,490
Income from investment in subsidiaries	159,653	105,198	(316,041)	388,253
Income (loss) from operations	144,820	78,146	(382,468)	280,763
Interest expense, net:
Interest expense	(91,589)	(84,044)	(263,428)	(172,699)
Interest income	8,478	3,592	19,615	11,644
Interest expense, net	(83,111)	(80,452)	(243,813)	(161,055)
Other non-operating expense
Bridge financing costs related to ICG				(49,490)
Net loss resulting from early retirement and refinancing of debt			(17,349)
Other nonoperating expense, Total			(17,349)	(49,490)
Income (loss) before income taxes	61,709	(2,306)	(643,630)	70,218
Provision for (benefit from) income taxes	15,958	(11,427)	(256,944)	(1,407)
Net income (loss)	45,751	9,121	(386,686)	71,625
Less: Net income attributable to noncontrolling interest		(231)	(268)	(822)
Net income (loss) attributable to Arch Coal, Inc.	45,751	8,890	(386,954)	70,803
Total comprehensive income (loss)	45,494	6,119	(385,185)	72,511
Guarantor Subsidiaries [Member]
Condensed Financial Statement Line Items
Revenues	1,087,618	1,198,673	3,190,807	3,057,139
Costs, expenses and other
Cost of sales	922,455	971,319	2,696,114	2,382,406
Depreciation, depletion and amortization	125,429	138,827	395,688	318,269
Amortization of acquired sales contracts, net	(4,093)	(12,698)	(22,561)	(5,492)
Legal contingencies	(79,532)		(79,532)
Mine closure and asset impairment costs	(2,194)		523,568	7,316
Goodwill impairment			115,791
Selling, general and administrative expenses	11,353	13,752	36,388	36,441
Change in fair value of coal derivatives and coal trading activities, net	5,840	8,360	(29,827)	9,248
Acquisition and transition costs related to ICG
Other operating (income) expense, net	(44,137)	(25,314)	(105,753)	(74,928)
Total operating expenses	935,121	1,094,246	3,529,876	2,673,260
Income from investment in subsidiaries
Income (loss) from operations	152,497	104,427	(339,069)	383,879
Interest expense, net:
Interest expense	(7,021)	(11,060)	(27,815)	(34,858)
Interest income	14,584	14,023	42,557	40,576
Interest expense, net	7,563	2,963	14,742	5,718
Other non-operating expense
Bridge financing costs related to ICG
Net loss resulting from early retirement and refinancing of debt		(1,708)	(1,693)	(1,958)
Other nonoperating expense, Total		(1,708)	(1,693)	(1,958)
Income (loss) before income taxes	160,060	105,682	(326,020)	387,639
Provision for (benefit from) income taxes
Net income (loss)	160,060	105,682	(326,020)	387,639
Less: Net income attributable to noncontrolling interest
Net income (loss) attributable to Arch Coal, Inc.	160,060	105,682	(326,020)	387,639
Total comprehensive income (loss)	158,864	101,255	(324,785)	379,390
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statement Line Items
Revenues
Costs, expenses and other
Cost of sales
Depreciation, depletion and amortization	9		24
Amortization of acquired sales contracts, net
Legal contingencies
Mine closure and asset impairment costs
Goodwill impairment
Selling, general and administrative expenses	1,783	1,058	5,871	2,439
Change in fair value of coal derivatives and coal trading activities, net
Acquisition and transition costs related to ICG
Other operating (income) expense, net	(89)	61	(12,449)	102
Total operating expenses	1,703	1,119	(6,554)	2,541
Income from investment in subsidiaries
Income (loss) from operations	(1,703)	(1,119)	6,554	(2,541)
Interest expense, net:
Interest expense	(649)	(541)	(2,382)	(1,535)
Interest income	1,946	1,176	5,811	4,690
Interest expense, net	1,297	635	3,429	3,155
Other non-operating expense
Bridge financing costs related to ICG
Net loss resulting from early retirement and refinancing of debt
Other nonoperating expense, Total
Income (loss) before income taxes	(406)	(484)	9,983	614
Provision for (benefit from) income taxes			1,581
Net income (loss)	(406)	(484)	8,402	614
Less: Net income attributable to noncontrolling interest
Net income (loss) attributable to Arch Coal, Inc.	(406)	(484)	8,402	614
Total comprehensive income (loss)	(406)	(484)	8,402	614
Eliminations [Member]
Condensed Financial Statement Line Items
Revenues
Costs, expenses and other
Cost of sales	(28,080)	(25,908)	(74,866)	(75,940)
Depreciation, depletion and amortization
Amortization of acquired sales contracts, net
Legal contingencies
Mine closure and asset impairment costs
Goodwill impairment
Selling, general and administrative expenses	(1,920)	(1,796)	(5,422)	(5,328)
Change in fair value of coal derivatives and coal trading activities, net
Acquisition and transition costs related to ICG
Other operating (income) expense, net	30,001	27,704	80,289	81,268
Total operating expenses	1		1
Income from investment in subsidiaries	(159,653)	(105,198)	316,041	(388,253)
Income (loss) from operations	(159,654)	(105,198)	316,040	(388,253)
Interest expense, net:
Interest expense	23,549	17,951	64,415	54,569
Interest income	(23,549)	(17,951)	(64,415)	(54,569)
Interest expense, net
Other non-operating expense
Bridge financing costs related to ICG
Net loss resulting from early retirement and refinancing of debt
Other nonoperating expense, Total
Income (loss) before income taxes	(159,654)	(105,198)	316,040	(388,253)
Provision for (benefit from) income taxes
Net income (loss)	(159,654)	(105,198)	316,040	(388,253)
Less: Net income attributable to noncontrolling interest
Net income (loss) attributable to Arch Coal, Inc.	(159,654)	(105,198)	316,040	(388,253)
Total comprehensive income (loss)	$ (159,653)	$ (105,198)	$ 316,044	$ (388,253)

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 550,756	$ 138,149	$ 158,509	$ 93,593
Restricted cash	3,450	10,322
Short term investments	99,359
Receivables	348,748	469,179
Inventories	391,526	377,490
Other	185,847	187,634
Total current assets	1,579,686	1,182,774
Property, plant and equipment, net	7,372,063	7,949,150
Investment in subsidiaries
Intercompany receivables
Note receivable from Arch Western
Other	984,105	1,082,035
Assets, Noncurrent	984,105	1,082,035
Total assets	9,935,854	10,213,959	9,961,657
Accounts payable	304,442	383,782
Accrued expenses and other current liabilities	358,946	356,035
Current maturities of debt and short-term borrowings	115,695	280,851
Total current liabilities	779,083	1,020,668
Long-term debt	4,465,445	3,762,297
Note payable to Arch Coal
Asset retirement obligations	426,044	446,784
Accrued pension benefits	45,160	48,244
Accrued postretirement benefits other than pension	41,061	42,309
Accrued workers' compensation	85,251	71,948
Deferred income taxes	746,079	976,753
Other noncurrent liabilities	182,464	255,382
Total liabilities	6,770,587	6,624,385
Redeemable noncontrolling interest		11,534
Stockholders' equity	3,165,267	3,578,040
Total liabilities and stockholders' equity	9,935,854	10,213,959
Parent/Issuer [Member]
Assets
Cash and cash equivalents	313,548	61,375	57,778	13,713
Restricted cash	3,450	10,322
Short term investments	99,359
Receivables	52,081	65,187
Inventories
Other	104,507	81,732
Total current assets	572,945	218,616
Property, plant and equipment, net	28,622	21,241
Investment in subsidiaries	8,503,465	8,805,731
Intercompany receivables	(1,399,215)	(1,457,864)
Note receivable from Arch Western	675,000	225,000
Other	184,982	184,266
Assets, Noncurrent	7,964,232	7,757,133
Total assets	8,565,799	7,996,990
Accounts payable	35,157	25,409
Accrued expenses and other current liabilities	92,337	75,133
Current maturities of debt and short-term borrowings	14,832	172,564
Total current liabilities	142,326	273,106
Long-term debt	4,463,386	3,308,674
Note payable to Arch Coal
Asset retirement obligations	790	877
Accrued pension benefits	21,125	19,198
Accrued postretirement benefits other than pension	11,733	13,843
Accrued workers' compensation	28,129	17,272
Deferred income taxes	665,414	621,483
Other noncurrent liabilities	67,629	152,963
Total liabilities	5,400,532	4,407,416
Redeemable noncontrolling interest		11,534
Stockholders' equity	3,165,267	3,578,040
Total liabilities and stockholders' equity	8,565,799	7,996,990
Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	225,431	75,425	100,419	79,880
Restricted cash
Short term investments
Receivables	24,672	27,001
Inventories	391,526	377,490
Other	80,901	105,282
Total current assets	722,530	585,198
Property, plant and equipment, net	7,343,360	7,918,816
Investment in subsidiaries
Intercompany receivables	1,561,073	1,716,424
Note receivable from Arch Western
Other	799,033	897,567
Assets, Noncurrent	2,360,106	2,613,991
Total assets	10,425,996	11,118,005
Accounts payable	269,203	358,347
Accrued expenses and other current liabilities	269,834	282,434
Current maturities of debt and short-term borrowings	863	1,987
Total current liabilities	539,900	642,768
Long-term debt	2,059	453,623
Note payable to Arch Coal	675,000	225,000
Asset retirement obligations	425,254	445,907
Accrued pension benefits	24,035	29,046
Accrued postretirement benefits other than pension	29,328	28,466
Accrued workers' compensation	57,122	54,676
Deferred income taxes	80,665	355,270
Other noncurrent liabilities	114,557	102,335
Total liabilities	1,947,920	2,337,091
Redeemable noncontrolling interest
Stockholders' equity	8,478,076	8,780,914
Total liabilities and stockholders' equity	10,425,996	11,118,005
Non-Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	11,777	1,349	312
Restricted cash
Short term investments
Receivables	276,992	378,608
Inventories
Other	439	620
Total current assets	289,208	380,577
Property, plant and equipment, net	81	9,093
Investment in subsidiaries
Intercompany receivables	(161,858)	(258,560)
Note receivable from Arch Western
Other	90	202
Assets, Noncurrent	(161,768)	(258,358)
Total assets	127,521	131,312
Accounts payable	82	26
Accrued expenses and other current liabilities	1,772	85
Current maturities of debt and short-term borrowings	100,000	106,300
Total current liabilities	101,854	106,411
Long-term debt
Note payable to Arch Coal
Asset retirement obligations
Accrued pension benefits
Accrued postretirement benefits other than pension
Accrued workers' compensation
Deferred income taxes
Other noncurrent liabilities	278	84
Total liabilities	102,132	106,495
Redeemable noncontrolling interest
Stockholders' equity	25,389	24,817
Total liabilities and stockholders' equity	127,521	131,312
Eliminations [Member]
Assets
Cash and cash equivalents
Restricted cash
Short term investments
Receivables	(4,997)	(1,617)
Inventories
Other
Total current assets	(4,997)	(1,617)
Property, plant and equipment, net
Investment in subsidiaries	(8,503,465)	(8,805,731)
Intercompany receivables
Note receivable from Arch Western	(675,000)	(225,000)
Other
Assets, Noncurrent	(9,178,465)	(9,030,731)
Total assets	(9,183,462)	(9,032,348)
Accounts payable
Accrued expenses and other current liabilities	(4,997)	(1,617)
Current maturities of debt and short-term borrowings
Total current liabilities	(4,997)	(1,617)
Long-term debt
Note payable to Arch Coal	(675,000)	(225,000)
Asset retirement obligations
Accrued pension benefits
Accrued postretirement benefits other than pension
Accrued workers' compensation
Deferred income taxes
Other noncurrent liabilities
Total liabilities	(679,997)	(226,617)
Redeemable noncontrolling interest
Stockholders' equity	(8,503,465)	(8,805,731)
Total liabilities and stockholders' equity	$ (9,183,462)	$ (9,032,348)

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash provided by (used in) operating activities	$ 356,395	$ 471,367
Investing Activities
Acquisition of ICG, net of cash acquired		(2,894,339)
Change in restricted cash	6,872	(5,939)
Capital expenditures	(303,968)	(215,899)
Proceeds from dispositions of property, plant and equipment	22,624	25,133
Investments in and advances to affiliates	(12,685)	(56,827)
Purchases of short term investments	(99,628)
Purchase of noncontrolling interest	(17,500)
Additions to prepaid royalties	(9,192)	(26,135)
Cash used in investing activities	(413,477)	(3,174,006)
Financing Activities
Proceeds from the issuance of senior notes		2,000,000
Proceeds from the sale of common stock, net		1,267,776
Contributions from parent
Proceeds from term note	1,386,000
Payments to retire debt	(452,806)	(604,096)
Net increase (decrease) in borrowings under lines of credit and commercial paper program	(381,300)	283,096
Payments on term note	(3,500)
Net payments on other debt	(13,078)	(8,792)
Debt financing costs	(34,686)	(114,587)
Dividends paid	(36,072)	(57,470)
Issuance of common stock under incentive plans	5,131	1,628
Transactions with affiliates, net
Cash provided by (used in) financing activities	469,689	2,767,555
Increase (decrease) in cash and cash equivalents	412,607	64,916
Cash and cash equivalents, beginning of period	138,149	93,593
Cash and cash equivalents, end of period	550,756	158,509
Parent/Issuer [Member]
Cash provided by (used in) operating activities	(500,331)	(444,664)
Investing Activities
Acquisition of ICG, net of cash acquired		(2,894,339)
Change in restricted cash	6,872	(5,939)
Capital expenditures	(4,150)	(5,137)
Proceeds from dispositions of property, plant and equipment
Investments in and advances to affiliates	(5,138)	(777,341)
Purchases of short term investments	(99,628)
Purchase of noncontrolling interest	(17,500)
Additions to prepaid royalties
Cash used in investing activities	(119,544)	(3,682,756)
Financing Activities
Proceeds from the issuance of senior notes		2,000,000
Proceeds from the sale of common stock, net		1,267,776
Contributions from parent
Proceeds from term note	1,386,000
Payments to retire debt
Net increase (decrease) in borrowings under lines of credit and commercial paper program	(381,300)	340,000
Payments on term note	(3,500)
Net payments on other debt	(13,078)	(8,792)
Debt financing costs	(34,640)	(114,563)
Dividends paid	(36,072)	(57,470)
Issuance of common stock under incentive plans	5,131	1,628
Transactions with affiliates, net	(50,493)	742,906
Cash provided by (used in) financing activities	872,048	4,171,485
Increase (decrease) in cash and cash equivalents	252,173	44,065
Cash and cash equivalents, beginning of period	61,375	13,713
Cash and cash equivalents, end of period	313,548	57,778
Guarantor Subsidiaries [Member]
Cash provided by (used in) operating activities	771,047	896,941
Investing Activities
Acquisition of ICG, net of cash acquired
Change in restricted cash
Capital expenditures	(299,818)	(210,660)
Proceeds from dispositions of property, plant and equipment	1,127	25,133
Investments in and advances to affiliates	(9,082)	(29,872)
Purchases of short term investments
Purchase of noncontrolling interest
Additions to prepaid royalties	(9,192)	(26,135)
Cash used in investing activities	(316,965)	(241,534)
Financing Activities
Proceeds from the issuance of senior notes
Proceeds from the sale of common stock, net
Contributions from parent	1,535	750,386
Proceeds from term note
Payments to retire debt	(452,806)	(604,096)
Net increase (decrease) in borrowings under lines of credit and commercial paper program		(56,904)
Payments on term note
Net payments on other debt
Debt financing costs		(16)
Dividends paid
Issuance of common stock under incentive plans
Transactions with affiliates, net	147,195	(724,238)
Cash provided by (used in) financing activities	(304,076)	(634,868)
Increase (decrease) in cash and cash equivalents	150,006	20,539
Cash and cash equivalents, beginning of period	75,425	79,880
Cash and cash equivalents, end of period	225,431	100,419
Non-Guarantor Subsidiaries [Member]
Cash provided by (used in) operating activities	85,679	19,090
Investing Activities
Acquisition of ICG, net of cash acquired
Change in restricted cash
Capital expenditures		(102)
Proceeds from dispositions of property, plant and equipment	21,497
Investments in and advances to affiliates
Purchases of short term investments
Purchase of noncontrolling interest
Additions to prepaid royalties
Cash used in investing activities	21,497	(102)
Financing Activities
Proceeds from the issuance of senior notes
Proceeds from the sale of common stock, net
Contributions from parent
Proceeds from term note
Payments to retire debt
Net increase (decrease) in borrowings under lines of credit and commercial paper program
Payments on term note
Net payments on other debt
Debt financing costs	(46)	(8)
Dividends paid
Issuance of common stock under incentive plans
Transactions with affiliates, net	(96,702)	(18,668)
Cash provided by (used in) financing activities	(96,748)	(18,676)
Increase (decrease) in cash and cash equivalents	10,428	312
Cash and cash equivalents, beginning of period	1,349
Cash and cash equivalents, end of period	11,777	312
Eliminations [Member]
Cash provided by (used in) operating activities
Investing Activities
Acquisition of ICG, net of cash acquired
Change in restricted cash
Capital expenditures
Proceeds from dispositions of property, plant and equipment
Investments in and advances to affiliates	1,535	750,386
Purchases of short term investments
Purchase of noncontrolling interest
Additions to prepaid royalties
Cash used in investing activities	1,535	750,386
Financing Activities
Proceeds from the issuance of senior notes
Proceeds from the sale of common stock, net
Contributions from parent	(1,535)	(750,386)
Proceeds from term note
Payments to retire debt
Net increase (decrease) in borrowings under lines of credit and commercial paper program
Payments on term note
Net payments on other debt
Debt financing costs
Dividends paid
Issuance of common stock under incentive plans
Transactions with affiliates, net
Cash provided by (used in) financing activities	(1,535)	(750,386)
Increase (decrease) in cash and cash equivalents
Cash and cash equivalents, beginning of period
Cash and cash equivalents, end of period